Input File Description

A string describing the task to be performed. Options are:
            

'scf'

'nscf'

'bands'

'relax'

'md'

'vc-relax'

'vc-md'

(vc = variable-cell).
            

reprinted on output.
         

Currently two verbosity levels are implemented:
            

'high'

'low'

'debug' and 'medium' have the same effect as 'high';
'default' and 'minimal' as 'low'
            

 Available options are:
            

'from_scratch' :

From scratch. This is the normal way to perform a PWscf calculation
            

'restart' :

From previous interrupted run. Use this switch only if you want to
continue, using the same number of processors and parallelization,
an interrupted calculation. Do not use to start a new one, or to
perform a non-scf calculations.  Works only if the calculation was
cleanly stopped using variable max_seconds, or by user request
with an "exit file" (i.e.: create a file "prefix".EXIT, in directory
"outdir"; see variables prefix, outdir). The default for
startingwfc and startingpot is set to 'file'.
            

 OBSOLETE - NO LONGER IMPLEMENTED
         

number of molecular-dynamics or structural optimization steps
performed in this run. If set to 0, the code performs a quick
"dry run", stopping just after initialization. This is useful
to check for input correctness and to have the summary printed.
NOTE: in MD calculations, the code will perform "nstep" steps
even if restarting from a previously interrupted calculation.
         

band energies are written every iprint iterations
         

calculate stress. It is set to .TRUE. automatically if
calculation == 'vc-md' or 'vc-relax'
         

calculate forces. It is set to .TRUE. automatically if
calculation == 'relax','md','vc-md'
         

time step for molecular dynamics, in Rydberg atomic units
(1 a.u.=4.8378 * 10^-17 s : beware, the CP code uses
 Hartree atomic units, half that much!!!)
         

input, temporary, output files are found in this directory,
see also wfcdir
         

This directory specifies where to store files generated by
each processor (*.wfc{N}, *.igk{N}, etc.). Useful for
machines without a parallel file system: set wfcdir to
a local file system, while outdir should be a parallel
or network file system, visible to all processors. Beware:
in order to restart from interrupted runs, or to perform
further calculations using the produced data files, you
may need to copy files to outdir. Works only for pw.x.
         

prepended to input/output filenames:
prefix.wfc, prefix.rho, etc.
         

OBSOLETE - NO LONGER IMPLEMENTED
         

Jobs stops after max_seconds CPU time. Use this option
in conjunction with option restart_mode if you need to
split a job too long to complete into shorter jobs that
fit into your batch queues.
         

Convergence threshold on total energy (a.u) for ionic
minimization: the convergence criterion is satisfied
when the total energy changes less than etot_conv_thr
between two consecutive scf steps. Note that etot_conv_thr
is extensive, like the total energy.
See also forc_conv_thr - both criteria must be satisfied
         

Convergence threshold on forces (a.u) for ionic minimization:
the convergence criterion is satisfied when all components of
all forces are smaller than forc_conv_thr.
See also etot_conv_thr - both criteria must be satisfied
         

Specifies the amount of disk I/O activity:
(only for binary files and xml data file in data directory;
other files printed at each molecular dynamics / structural
optimization step are not controlled by this option )
            

'high' :

save charge to disk at each SCF step,
keep wavefunctions on disk (in "distributed" format),
save mixing data as well.
Do not use this option unless you have a good reason!
It is no longer needed to specify 'high' in order to be able
to restart from an interrupted calculation (see restart_mode)
            

'medium' :

save charge to disk at each SCF step,
keep wavefunctions on disk only if more than one k-point,
per process is present, otherwise keep them in memory;
save them to disk only at the end (in "portable" format)
            

'low' :

save charge to disk at each SCF step,
keep wavefunctions in memory (for all k-points),
save them to disk only at the end (in "portable" format).
Reduces I/O but increases memory wrt the previous cases
            

'nowf' :

save to disk only the xml data file,
never save wavefunctions and charge density
            

'none' :

do not save anything to disk
            

Default is 'low' for the scf case, 'medium' otherwise.
Note that the needed RAM increases as disk I/O decreases
            

directory containing pseudopotential files
         

If .TRUE. a saw-like potential simulating an electric field
is added to the bare ionic potential. See variables edir,
eamp, emaxpos, eopreg for the form and size of
the added potential.
         

If .TRUE. and tefield==.TRUE. a dipole correction is also
added to the bare ionic potential - implements the recipe
of L. Bengtsson, PRB 59, 12301 (1999). See variables edir,
emaxpos, eopreg for the form of the correction. Must
be used ONLY in a slab geometry, for surface calculations,
with the discontinuity FALLING IN THE EMPTY SPACE.
         

If .TRUE. a homogeneous finite electric field described
through the modern theory of the polarization is applied.
This is different from tefield == .true. !
         

In the case of a finite electric field  ( lelfield == .TRUE. )
it defines the number of iterations for converging the
wavefunctions in the electric field Hamiltonian, for each
external iteration on the charge density
         

If .TRUE. perform orbital magnetization calculation.
If finite electric field is applied (lelfield==.true.) only Kubo terms are computed
[for details see New J. Phys. 12, 053032 (2010), doi:10.1088/1367-2630/12/5/053032].

The type of calculation is 'nscf' and should be performed on an automatically
generated uniform grid of k points.

Works ONLY with norm-conserving pseudopotentials.
         

If .TRUE. perform a Berry phase calculation.
See the header of PW/src/bp_c_phase.f90 for documentation.
         

For Berry phase calculation: direction of the k-point
strings in reciprocal space. Allowed values: 1, 2, 3
1=first, 2=second, 3=third reciprocal lattice vector
For calculations with finite electric fields
(lelfield==.true.) "gdir" is the direction of the field.
         

For Berry phase calculation: number of k-points to be
calculated along each symmetry-reduced string.
The same for calculation with finite electric fields
(lelfield==.true.).
         

In the case of charged cells (tot_charge .ne. 0) setting gate = .TRUE.
represents the counter charge (i.e. -tot_charge) not by a homogeneous
background charge but with a charged plate, which is placed at zgate
(see below). Details of the gate potential can be found in
T. Brumme, M. Calandra, F. Mauri; PRB 89, 245406 (2014).
Note, that in systems which are not symmetric with respect to the plate,
one needs to enable the dipole correction! (dipfield=.true.).
Currently, symmetry can be used with gate=.true. but carefully check
that no symmetry is included which maps z to -z even if in principle one
could still use them for symmetric systems (i.e. no dipole correction).
For nosym=.false. verbosity is set to 'high'.
Note: this option was called "monopole" in v6.0 and 6.1 of pw.x
         

If .TRUE. perform a constant bias potential (constant-mu) calculation
for a system with ESM method. See the header of PW/src/fcp_module.f90
for documentation. To perform the calculation, you must set a namelist FCP.

NB:
- The total energy displayed in output includes the potentiostat
  contribution (-mu*N).
- calculation must be 'relax' or 'md'.
- assume_isolated = 'esm' and esm_bc = 'bc2' or 'bc3' must be set
  in SYSTEM namelist.
- ESM-RISM is also supported (assume_isolated = 'esm' and esm_bc = 'bc1'
  and trism = .TRUE.).
- ignore_wolfe is always .TRUE., for BFGS.
         

If .TRUE. perform a 3D-RISM-SCF calculation
[for details see H.Sato et al., JCP 112, 9463 (2000), doi:10.1063/1.481564].
The solvent's distributions are calculated by 3D-RISM,
though solute is treated as SCF. The charge density and
the atomic positions are optimized, simultaneously with
the solvents. To perform the calculation, you must set
a namelist RISM and a card SOLVENTS.

If assume_isolated = 'esm' and esm_bc = 'bc1',
Laue-RISM is calculated instead of 3D-RISM
and coupled with ESM method (i.e. ESM-RISM).
[for details see S.Nishihara and M.Otani, PRB 96, 115429 (2017)].

The default of mixing_beta is 0.2
for both 3D-RISM and Laue-RISM.

For structural relaxation with BFGS,
ignore_wolfe is always .TRUE. .
         

  Bravais-lattice index. Optional only if space_group is set.
  If ibrav /= 0, specify EITHER [ celldm(1)-celldm(6) ]
  OR [ A, B, C, cosAB, cosAC, cosBC ]
  but NOT both. The lattice parameter "alat" is set to
  alat = celldm(1) (in a.u.) or alat = A (in Angstrom);
  see below for the other parameters.
  For ibrav=0 specify the lattice vectors in CELL_PARAMETERS,
  optionally the lattice parameter alat = celldm(1) (in a.u.)
  or = A (in Angstrom). If not specified, the lattice parameter is
  taken from CELL_PARAMETERS
  IMPORTANT NOTICE 1:
  with ibrav=0 lattice vectors must be given with a sufficiently large
  number of digits and with the correct symmetry, or else symmetry
  detection may fail and strange problems may arise in symmetrization.
  IMPORTANT NOTICE 2:
  do not use celldm(1) or A as a.u. to Ang conversion factor,
  use the true lattice parameters or nothing,
  specify units in CELL_PARAMETERS and ATOMIC_POSITIONS

ibrav      structure                   celldm(2)-celldm(6)
                                     or: b,c,cosbc,cosac,cosab
  0          free
      crystal axis provided in input: see card CELL_PARAMETERS

  1          cubic P (sc)
      v1 = a(1,0,0),  v2 = a(0,1,0),  v3 = a(0,0,1)

  2          cubic F (fcc)
      v1 = (a/2)(-1,0,1),  v2 = (a/2)(0,1,1), v3 = (a/2)(-1,1,0)

  3          cubic I (bcc)
      v1 = (a/2)(1,1,1),  v2 = (a/2)(-1,1,1),  v3 = (a/2)(-1,-1,1)
 -3          cubic I (bcc), more symmetric axis:
      v1 = (a/2)(-1,1,1), v2 = (a/2)(1,-1,1),  v3 = (a/2)(1,1,-1)

  4          Hexagonal and Trigonal P        celldm(3)=c/a
      v1 = a(1,0,0),  v2 = a(-1/2,sqrt(3)/2,0),  v3 = a(0,0,c/a)

  5          Trigonal R, 3fold axis c        celldm(4)=cos(gamma)
      The crystallographic vectors form a three-fold star around
      the z-axis, the primitive cell is a simple rhombohedron:
      v1 = a(tx,-ty,tz),   v2 = a(0,2ty,tz),   v3 = a(-tx,-ty,tz)
      where c=cos(gamma) is the cosine of the angle gamma between
      any pair of crystallographic vectors, tx, ty, tz are:
        tx=sqrt((1-c)/2), ty=sqrt((1-c)/6), tz=sqrt((1+2c)/3)
 -5          Trigonal R, 3fold axis <111>    celldm(4)=cos(gamma)
      The crystallographic vectors form a three-fold star around
      <111>. Defining a' = a/sqrt(3) :
      v1 = a' (u,v,v),   v2 = a' (v,u,v),   v3 = a' (v,v,u)
      where u and v are defined as
        u = tz - 2*sqrt(2)*ty,  v = tz + sqrt(2)*ty
      and tx, ty, tz as for case ibrav=5
      Note: if you prefer x,y,z as axis in the cubic limit,
            set  u = tz + 2*sqrt(2)*ty,  v = tz - sqrt(2)*ty
            See also the note in Modules/latgen.f90

  6          Tetragonal P (st)               celldm(3)=c/a
      v1 = a(1,0,0),  v2 = a(0,1,0),  v3 = a(0,0,c/a)

  7          Tetragonal I (bct)              celldm(3)=c/a
      v1=(a/2)(1,-1,c/a),  v2=(a/2)(1,1,c/a),  v3=(a/2)(-1,-1,c/a)

  8          Orthorhombic P                  celldm(2)=b/a
                                             celldm(3)=c/a
      v1 = (a,0,0),  v2 = (0,b,0), v3 = (0,0,c)

  9          Orthorhombic base-centered(bco) celldm(2)=b/a
                                             celldm(3)=c/a
      v1 = (a/2, b/2,0),  v2 = (-a/2,b/2,0),  v3 = (0,0,c)
 -9          as 9, alternate description
      v1 = (a/2,-b/2,0),  v2 = (a/2, b/2,0),  v3 = (0,0,c)
 91          Orthorhombic one-face base-centered A-type
                                             celldm(2)=b/a
                                             celldm(3)=c/a
      v1 = (a, 0, 0),  v2 = (0,b/2,-c/2),  v3 = (0,b/2,c/2)

 10          Orthorhombic face-centered      celldm(2)=b/a
                                             celldm(3)=c/a
      v1 = (a/2,0,c/2),  v2 = (a/2,b/2,0),  v3 = (0,b/2,c/2)

 11          Orthorhombic body-centered      celldm(2)=b/a
                                             celldm(3)=c/a
      v1=(a/2,b/2,c/2),  v2=(-a/2,b/2,c/2),  v3=(-a/2,-b/2,c/2)

 12          Monoclinic P, unique axis c     celldm(2)=b/a
                                             celldm(3)=c/a,
                                             celldm(4)=cos(ab)
      v1=(a,0,0), v2=(b*cos(gamma),b*sin(gamma),0),  v3 = (0,0,c)
      where gamma is the angle between axis a and b.
-12          Monoclinic P, unique axis b     celldm(2)=b/a
                                             celldm(3)=c/a,
                                             celldm(5)=cos(ac)
      v1 = (a,0,0), v2 = (0,b,0), v3 = (c*cos(beta),0,c*sin(beta))
      where beta is the angle between axis a and c

 13          Monoclinic base-centered        celldm(2)=b/a
             (unique axis c)                 celldm(3)=c/a,
                                             celldm(4)=cos(gamma)
      v1 = (  a/2,         0,          -c/2),
      v2 = (b*cos(gamma), b*sin(gamma), 0  ),
      v3 = (  a/2,         0,           c/2),
      where gamma=angle between axis a and b projected on xy plane

-13          Monoclinic base-centered        celldm(2)=b/a
             (unique axis b)                 celldm(3)=c/a,
                                             celldm(5)=cos(beta)
      v1 = (  a/2,       b/2,             0),
      v2 = ( -a/2,       b/2,             0),
      v3 = (c*cos(beta),   0,   c*sin(beta)),
      where beta=angle between axis a and c projected on xz plane
 IMPORTANT NOTICE: until QE v.6.4.1, axis for ibrav=-13 had a
 different definition: v1(old) =-v2(now), v2(old) = v1(now)

 14          Triclinic                       celldm(2)= b/a,
                                             celldm(3)= c/a,
                                             celldm(4)= cos(bc),
                                             celldm(5)= cos(ac),
                                             celldm(6)= cos(ab)
      v1 = (a, 0, 0),
      v2 = (b*cos(gamma), b*sin(gamma), 0)
      v3 = (c*cos(beta),  c*(cos(alpha)-cos(beta)cos(gamma))/sin(gamma),
           c*sqrt( 1 + 2*cos(alpha)cos(beta)cos(gamma)
                     - cos(alpha)^2-cos(beta)^2-cos(gamma)^2 )/sin(gamma) )
      where alpha is the angle between axis b and c
             beta is the angle between axis a and c
            gamma is the angle between axis a and b
         

Either:

Or:

number of atoms in the unit cell (ALL atoms, except if
space_group is set, in which case, INEQUIVALENT atoms)
         

number of types of atoms in the unit cell
         

Number of electronic states (bands) to be calculated.
Note that in spin-polarized calculations the number of
k-point, not the number of bands per k-point, is doubled
         

Total charge of the system. Useful for simulations with charged cells.
By default the unit cell is assumed to be neutral (tot_charge=0).
tot_charge=+1 means one electron missing from the system,
tot_charge=-1 means one additional electron, and so on.

In a periodic calculation a compensating jellium background is
inserted to remove divergences if the cell is not neutral.
         

starting charge on atomic type 'i',
to create starting potential with startingpot = 'atomic'.
         

Total majority spin charge - minority spin charge.
Used to impose a specific total electronic magnetization.
If unspecified then tot_magnetization variable is ignored and
the amount of electronic magnetization is determined during
the self-consistent cycle.
         

Starting spin polarization on atomic type 'i' in a spin
polarized (LSDA or noncollinear/spin-orbit) calculation.
Allowed values range between -1 (all spins down for the
valence electrons of atom type 'i') to 1 (all spins up).
If you expect a nonzero magnetization in your ground state,
you MUST either specify a nonzero value for at least one
atomic type, or constrain the magnetization using variable
tot_magnetization for LSDA, constrained_magnetization
for noncollinear/spin-orbit calculations. If you don't,
you will get a nonmagnetic (zero magnetization) state.
In order to perform LSDA calculations for an antiferromagnetic
state, define two different atomic species corresponding to
sublattices of the same atomic type.

NOTE 1: starting_magnetization is ignored in most BUT NOT ALL
cases in non-scf calculations: it is safe to keep the same
values for the scf and subsequent non-scf calculation.

NOTE 2: If you fix the magnetization with
tot_magnetization, do not specify starting_magnetization.

NOTE 3: In the noncollinear/spin-orbit case, starting with zero
starting_magnetization on all atoms imposes time reversal
symmetry. The magnetization is never calculated and is
set to zero (the internal variable domag is set to .FALSE.).
         

kinetic energy cutoff (Ry) for wavefunctions
         

Kinetic energy cutoff (Ry) for charge density and potential
For norm-conserving pseudopotential you should stick to the
default value, you can reduce it by a little but it will
introduce noise especially on forces and stress.
If there are ultrasoft PP, a larger value than the default is
often desirable (ecutrho = 8 to 12 times ecutwfc, typically).
PAW datasets can often be used at 4*ecutwfc, but it depends
on the shape of augmentation charge: testing is mandatory.
The use of gradient-corrected functional, especially in cells
with vacuum, or for pseudopotential without non-linear core
correction, usually requires an higher values of ecutrho
to be accurately converged.
         

Kinetic energy cutoff (Ry) for the exact exchange operator in
EXX type calculations. By default this is the same as ecutrho
but in some EXX calculations, a significant speed-up can be obtained
by reducing ecutfock, at the expense of some loss in accuracy.
Must be .gt. ecutwfc. Not implemented for stress calculation
and for US-PP and PAW pseudopotentials.
Use with care, especially in metals where it may give raise
to instabilities.
         

Three-dimensional FFT mesh (hard grid) for charge
density (and scf potential). If not specified
the grid is calculated based on the cutoff for
charge density (see also ecutrho)
Note: you must specify all three dimensions for this setting to
be used.
         

Three-dimensional mesh for wavefunction FFT and for the smooth
part of charge density ( smooth grid ).
Coincides with nr1, nr2, nr3 if ecutrho = 4 * ecutwfc ( default )
Note: you must specify all three dimensions for this setting to
be used.
         

if (.TRUE.) symmetry is not used. Consequences:

- if a list of k points is provided in input, it is used
  "as is": symmetry-inequivalent k-points are not generated,
  and the charge density is not symmetrized;

- if a uniform (Monkhorst-Pack) k-point grid is provided in
  input, it is expanded to cover the entire Brillouin Zone,
  irrespective of the crystal symmetry.
  Time reversal symmetry is assumed so k and -k are considered
  as equivalent unless noinv=.true. is specified.

Do not use this option unless you know exactly what you want
and what you get. May be useful in the following cases:
- in low-symmetry large cells, if you cannot afford a k-point
  grid with the correct symmetry
- in MD simulations
- in calculations for isolated atoms
         

if (.TRUE.) symmetry is not used, and k points are
forced to have the symmetry of the Bravais lattice;
an automatically generated Monkhorst-Pack grid will contain
all points of the grid over the entire Brillouin Zone,
plus the points rotated by the symmetries of the Bravais
lattice which were not in the original grid. The same
applies if a k-point list is provided in input instead
of a Monkhorst-Pack grid. Time reversal symmetry is assumed
so k and -k are equivalent unless noinv=.true. is specified.
This option differs from nosym because it forces k-points
in all cases to have the full symmetry of the Bravais lattice
(not all uniform grids have such property!)
         

if (.TRUE.) disable the usage of k => -k symmetry
(time reversal) in k-point generation
         

if (.TRUE.) disable the usage of magnetic symmetry operations
that consist in a rotation + time reversal.
         

if (.TRUE.) force the symmetry group to be symmorphic by disabling
symmetry operations having an associated fractionary translation
         

if (.FALSE.) force real-space FFT grids to be commensurate with
fractionary translations of non-symmorphic symmetry operations,
if present (e.g.: if a fractional translation (0,0,c/4) exists,
the FFT dimension along the c axis must be multiple of 4).
if (.TRUE.) do not impose any constraints to FFT grids, even in
the presence of non-symmorphic symmetry operations.
BEWARE: use_all_frac=.TRUE. may lead to wrong results for
hybrid functionals and phonon calculations. Both cases use
symmetrization in real space that works for non-symmorphic
operations only if the real-space FFT grids are commensurate.
         

 Available options are:
            

'smearing' :

gaussian smearing for metals;
see variables smearing and degauss
            

'tetrahedra' :

Tetrahedron method, Bloechl's version:
P.E. Bloechl, PRB 49, 16223 (1994)
Requires uniform grid of k-points, to be
automatically generated (see card K_POINTS).
Well suited for calculation of DOS,
less so (because not variational) for
force/optimization/dynamics calculations.
            

'tetrahedra_lin' :

Original linear tetrahedron method.
To be used only as a reference;
the optimized tetrahedron method is more efficient.
            

'tetrahedra_opt' :

Optimized tetrahedron method:
see M. Kawamura, PRB 89, 094515 (2014).
Can be used for phonon calculations as well.
            

'fixed' :

for insulators with a gap
            

'from_input' :

The occupation are read from input file,
card OCCUPATIONS. Option valid only for a
single k-point, requires nbnd to be set
in input. Occupations should be consistent
with the value of tot_charge.
            

This flag is used for isolated atoms (nat=1) together with
occupations='from_input'. If it is .TRUE., the wavefunctions
are ordered as the atomic starting wavefunctions, independently
from their eigenvalue. The occupations indicate which atomic
states are filled.

The order of the states is written inside the UPF pseudopotential file.
In the scalar relativistic case:
S -> l=0, m=0
P -> l=1, z, x, y
D -> l=2, r^2-3z^2, xz, yz, xy, x^2-y^2

In the noncollinear magnetic case (with or without spin-orbit),
each group of states is doubled. For instance:
P -> l=1, z, x, y for spin up, l=1, z, x, y for spin down.
Up and down is relative to the direction of the starting
magnetization.

In the case with spin-orbit and time-reversal
(starting_magnetization=0.0) the atomic wavefunctions are
radial functions multiplied by spin-angle functions.
For instance:
P -> l=1, j=1/2, m_j=-1/2,1/2. l=1, j=3/2,
     m_j=-3/2, -1/2, 1/2, 3/2.

In the magnetic case with spin-orbit the atomic wavefunctions
can be forced to be spin-angle functions by setting
starting_spin_angle to .TRUE..
         

In the spin-orbit case when domag=.TRUE., by default,
the starting wavefunctions are initialized as in scalar
relativistic noncollinear case without spin-orbit.

By setting starting_spin_angle=.TRUE. this behaviour can
be changed and the initial wavefunctions are radial
functions multiplied by spin-angle functions.

When domag=.FALSE. the initial wavefunctions are always
radial functions multiplied by spin-angle functions
independently from this flag.

When lspinorb is .FALSE. this flag is not used.
         

value of the gaussian spreading (Ry) for brillouin-zone
integration in metals.
         

Available options are:
            

'gaussian', 'gauss' :

ordinary Gaussian spreading (Default)
            

'methfessel-paxton', 'm-p', 'mp' :

Methfessel-Paxton first-order spreading
(see PRB 40, 3616 (1989)).
            

'marzari-vanderbilt', 'cold', 'm-v', 'mv' :

Marzari-Vanderbilt-DeVita-Payne cold smearing
(see PRL 82, 3296 (1999))
            

'fermi-dirac', 'f-d', 'fd' :

smearing with Fermi-Dirac function
            

nspin = 1 :  non-polarized calculation (default)

nspin = 2 :  spin-polarized calculation, LSDA
             (magnetization along z axis)

nspin = 4 :  spin-polarized calculation, noncollinear
             (magnetization in generic direction)
             DO NOT specify nspin in this case;
             specify noncolin=.TRUE. instead
         

if .true. the program will perform a noncollinear calculation.
         

ecfixed, qcutz, q2sigma:  parameters for modified functional to be
used in variable-cell molecular dynamics (or in stress calculation).
"ecfixed" is the value (in Rydberg) of the constant-cutoff;
"qcutz" and "q2sigma" are the height and the width (in Rydberg)
of the energy step for reciprocal vectors whose square modulus
is greater than "ecfixed". In the kinetic energy, G^2 is
replaced by G^2 + qcutz * (1 + erf ( (G^2 - ecfixed)/q2sigma) )
See: M. Bernasconi et al, J. Phys. Chem. Solids 56, 501 (1995),
doi:10.1016/0022-3697(94)00228-2
         

Exchange-correlation functional: eg 'PBE', 'BLYP' etc
See Modules/funct.f90 for allowed values.
Overrides the value read from pseudopotential files.
Use with care and if you know what you are doing!
         

Use Adaptively Compressed Exchange operator as in
Lin Lin, J. Chem. Theory Comput. 2016, 12, 2242--2249, doi:10.1021/acs.jctc.6b00092

Set to false to use standard Exchange (much slower)
         

Fraction of EXX for hybrid functional calculations. In the case of
input_dft='PBE0', the default value is 0.25, while for input_dft='B3LYP'
the exx_fraction default value is 0.20.
         

screening_parameter for HSE like hybrid functionals.
For more information, see:
J. Chem. Phys. 118, 8207 (2003), doi:10.1063/1.1564060
J. Chem. Phys. 124, 219906 (2006), doi:10.1063/1.2204597
         

Specific for EXX. It selects the kind of approach to be used
for treating the Coulomb potential divergencies at small q vectors.
            

'gygi-baldereschi' :

 appropriate for cubic and quasi-cubic supercells
            

'vcut_spherical' :

 appropriate for cubic and quasi-cubic supercells
            

'vcut_ws' :

 appropriate for strongly anisotropic supercells, see also ecutvcut.
            

'none' :

 sets Coulomb potential at G,q=0 to 0.0 (required for GAU-PBE)
            

Specific for EXX. If .true., extrapolate the G=0 term of the
potential (see README in examples/EXX_example for more)
Set this to .false. for GAU-PBE.
         

Reciprocal space cutoff for correcting Coulomb potential
divergencies at small q vectors.
         

Three-dimensional mesh for q (k1-k2) sampling of
the Fock operator (EXX). Can be smaller than
the number of k-points.

Currently this defaults to the size of the k-point mesh used.
In QE =< 5.0.2 it defaulted to nqx1=nqx2=nqx3=1.
         

Overlap threshold over which the exchange integral over a pair of localized orbitals
is included in the evaluation of EXX operator. Any value greater than 0.0 triggers
the SCDM localization and the evaluation on EXX using the localized orbitals.
Very small value of the threshold should yield the same result as the default EXX
evaluation
         

Hubbard occupations is the number of electrons in the
Hubbard manifold. By default they are initialized by
reading the occupations from pseudopotentials. If specified
from the input, then the values read from the pseudopotentials
will be overwritten.
The second index of the Hubbard_occ array corresponds to the
Hubbard manifold number. It is possible to specify up to
three Hubbard manifolds per Hubbard atom. However, if you want
to specify three manifolds then the second and the third manifolds
will be considered as one effective manifold (see Doc/Hubbard_input.pdf)
         

Hubbard_alpha(i) is the perturbation (on atom i, in eV)
used to compute U (and V) with the linear-response method of
Cococcioni and de Gironcoli, PRB 71, 035105 (2005)
(only for lda_plus_u_kind=0 and 2).

Note: Hubbard U and V can be computed using the HP code
which is based on density-functional perturbation theory,
and it gives exactly the same result as the method of
Cococcioni and de Gironcoli.
         

Hubbard_beta(i) is the perturbation (on atom i, in eV)
used to compute J0 with the linear-response method of
Cococcioni and de Gironcoli, PRB 71, 035105 (2005)
(only for lda_plus_u_kind=0 and 2). See also
PRB 84, 115108 (2011).
         

In the first iteration of an DFT+U run it overwrites
the m-th eigenvalue of the ns occupation matrix for the
ispin component of atomic species ityp.
For the noncollinear case, the ispin index runs up to npol=2
The value lmax  is given by the maximum angular momentum
number to which the Hubbard U is applied.
Leave unchanged eigenvalues that are not set.
This is useful to suggest the desired orbital occupations
when the default choice takes another path.
         

If true, nscf calculation will exit in restart mode, scf calculation
will restart from there if DMFT updates are provided as hdf5 archive.
Scf calculation should be used only with electron_maxstep = 1.
K_POINTS have to be identical and given explicitly with nosym.
         

prepended to hdf5 archive: dmft_prefix.h5

DMFT update should be provided in group/dataset as:
- dft_misc_input/band_window with dimension [1, number of k-points, 2 (real + complex)]
- dft_update/delta_N with dimension [number of k-points, number of correlated orbitals,
number of correlated orbitals, 2 (real + complex)]
         

If ensemble_energies = .true., an ensemble of xc energies
is calculated non-selfconsistently for perturbed
exchange-enhancement factors and LDA vs. PBE correlation
ratios after each converged electronic ground state
calculation.

Ensemble energies can be analyzed with the 'bee' utility
included with libbeef.

Requires linking against libbeef.
input_dft must be set to a BEEF-type functional
(e.g. input_dft = 'BEEF-vdW')
         

The direction of the electric field or dipole correction is
parallel to the bg(:,edir) reciprocal lattice vector, so the
potential is constant in planes defined by FFT grid points;
edir = 1, 2 or 3. Used only if tefield is .TRUE.
         

Position of the maximum of the saw-like potential along crystal
axis edir, within the  unit cell (see below), 0 < emaxpos < 1
Used only if tefield is .TRUE.
         

Zone in the unit cell where the saw-like potential decreases.
( see below, 0 < eopreg < 1 ). Used only if tefield is .TRUE.
         

Amplitude of the electric field, in ***Hartree*** a.u.;
1 a.u. = 51.4220632*10^10 V/m. Used only if tefield==.TRUE.
The saw-like potential increases with slope eamp in the
region from (emaxpos+eopreg-1) to (emaxpos), then decreases
to 0 until (emaxpos+eopreg), in units of the crystal
vector edir. Important: the change of slope of this
potential must be located in the empty region, or else
unphysical forces will result.
         

The angle expressed in degrees between the initial
magnetization and the z-axis. For noncollinear calculations
only; index i runs over the atom types.
         

The angle expressed in degrees between the projection
of the initial magnetization on x-y plane and the x-axis.
For noncollinear calculations only.
         

When starting a non collinear calculation using an existing density
file from a collinear lsda calculation assumes previous density points in
z direction and rotates it in the direction described by angle1 and
angle2 variables for atomic type 1
         

Used to perform constrained calculations in magnetic systems.
Currently available choices:
            

'none' :

no constraint
            

'total' :

total magnetization is constrained by
adding a penalty functional to the total energy:

LAMBDA * SUM_{i} ( magnetization(i) - fixed_magnetization(i) )**2

where the sum over i runs over the three components of
the magnetization. Lambda is a real number (see below).
Noncolinear case only. Use tot_magnetization for LSDA
            

'atomic' :

atomic magnetization are constrained to the defined
starting magnetization adding a penalty:

LAMBDA * SUM_{i,itype} ( magnetic_moment(i,itype) - mcons(i,itype) )**2

where i runs over the cartesian components (or just z
in the collinear case) and itype over the types (1-ntype).
mcons(:,:) array is defined from starting_magnetization,
(also from angle1, angle2 in the noncollinear case).
lambda is a real number
            

'total direction' :

the angle theta of the total magnetization
with the z axis (theta = fixed_magnetization(3))
is constrained:

LAMBDA * ( arccos(magnetization(3)/mag_tot) - theta )**2

where mag_tot is the modulus of the total magnetization.
            

'atomic direction' :

not all the components of the atomic
magnetic moment are constrained but only the cosine
of angle1, and the penalty functional is:

LAMBDA * SUM_{itype} ( mag_mom(3,itype)/mag_mom_tot - cos(angle1(ityp)) )**2
            

N.B.: symmetrization may prevent to reach the desired orientation
of the magnetization. Try not to start with very highly symmetric
configurations or use the nosym flag (only as a last remedy)
            

total magnetization vector (x,y,z components) to be kept
fixed when constrained_magnetization=='total'
         

parameter used for constrained_magnetization calculations
N.B.: if the scf calculation does not converge, try to reduce lambda
      to obtain convergence, then restart the run with a larger lambda
         

determines when atomic magnetic moments are printed on output:
report = 0  never
report =-1  at the beginning of the scf and at convergence
report = N  as -1, plus every N scf iterations
         

if .TRUE. the noncollinear code can use a pseudopotential with
spin-orbit.
         

Used to perform calculation assuming the system to be
isolated (a molecule or a cluster in a 3D supercell).

Currently available choices:
            

'none' :

(default): regular periodic calculation w/o any correction.
            

'makov-payne', 'm-p', 'mp' :

the Makov-Payne correction to the
total energy is computed. An estimate of the vacuum
level is also calculated so that eigenvalues can be
properly aligned. ONLY FOR CUBIC SYSTEMS (ibrav=1,2,3).
Theory: G.Makov, and M.C.Payne,
     "Periodic boundary conditions in ab initio
     calculations" , PRB 51, 4014 (1995).
            

'martyna-tuckerman', 'm-t', 'mt' :

Martyna-Tuckerman correction
to both total energy and scf potential. Adapted from:
G.J. Martyna, and M.E. Tuckerman,
"A reciprocal space based method for treating long
range interactions in ab-initio and force-field-based
calculation in clusters", J. Chem. Phys. 110, 2810 (1999),
doi:10.1063/1.477923.
            

'esm' :

Effective Screening Medium Method.
For polarized or charged slab calculation, embeds
the simulation cell within an effective semi-
infinite medium in the perpendicular direction
(along z). Embedding regions can be vacuum or
semi-infinite metal electrodes (use esm_bc to
choose boundary conditions). If between two
electrodes, an optional electric field
(esm_efield) may be applied. Method described in
M. Otani and O. Sugino, "First-principles calculations
of charged surfaces and interfaces: A plane-wave
nonrepeated slab approach", PRB 73, 115407 (2006).

NB:
   - Two dimensional (xy plane) average charge density
     and electrostatic potentials are printed out to
     'prefix.esm1'.

   - Requires cell with a_3 lattice vector along z,
     normal to the xy plane, with the slab centered
     around z=0.

   - For bc2 with an electric field and bc3 boundary
     conditions, the inversion symmetry along z-direction
     is automatically eliminated.

   - In case of calculation='vc-relax', use
     cell_dofree='2Dxy' or other parameters so that
     c-vector along z-axis should not be moved.

See esm_bc, esm_efield, esm_w, esm_nfit.
            

'2D' :

Truncation of the Coulomb interaction in the z direction
for structures periodic in the x-y plane. Total energy,
forces and stresses are computed in a two-dimensional framework.
Linear-response calculations () done on top of a self-consistent
calculation with this flag will automatically be performed in
the 2D framework as well. Please refer to:
Sohier, T., Calandra, M., & Mauri, F. (2017), "Density functional
perturbation theory for gated two-dimensional heterostructures:
Theoretical developments and application to flexural phonons in graphene",
PRB, 96, 075448 (2017).

NB:
   - The length of the unit-cell along the z direction should
     be larger than twice the thickness of the 2D material
     (including electrons). A reasonable estimate for a
     layer's thickness could be the interlayer distance in the
     corresponding layered bulk material. Otherwise,
     the atomic thickness + 10 bohr should be a safe estimate.
     There is also a lower limit of 20 bohr imposed by the cutoff
     radius used to read pseudopotentials (see read_pseudo.f90 in Modules).

   - As for ESM above, only in-plane stresses make sense and one
     should use cell_dofree= '2Dxy' in a vc-relax calculation.
            

If assume_isolated = 'esm', determines the boundary
conditions used for either side of the slab.

Currently available choices:
            

'pbc' :

 (default): regular periodic calculation (no ESM).
            

'bc1' :

 Vacuum-slab-vacuum (open boundary conditions).
            

'bc2' :

Metal-slab-metal (dual electrode configuration).
See also esm_efield.
            

'bc3' :

 Vacuum-slab-metal
            

If assume_isolated = 'esm', determines the position offset
[in a.u.] of the start of the effective screening region,
measured relative to the cell edge. (ESM region begins at
z = +/- [L_z/2 + esm_w] ).
         

If assume_isolated = 'esm' and esm_bc = 'bc2', gives the
magnitude of the electric field [Ry/a.u.] to be applied
between semi-infinite ESM electrodes.
         

If assume_isolated = 'esm', gives the number of z-grid points
for the polynomial fit along the cell edge.
         

If .TRUE. perform a constant bias potential (constant-mu) calculation
with Grand-Canonical SCF. (JCP 146, 114104 (2017), R.Sundararaman, et al.)

NB:
- The total energy displayed in output includes the potentiostat
  contribution (-mu*N).
- assume_isolated = 'esm' and esm_bc = 'bc2' or 'bc3' must be set
  in SYSTEM namelist.
- ESM-RISM is also supported (assume_isolated = 'esm' and esm_bc = 'bc1'
  and trism = .TRUE.).
- mixing_mode has to be 'TF' or 'local-TF', also its default is 'TF.'
- The default of mixing_beta is 0.1 with ESM-RISM, 0.2 without ESM-RISM.
- The default of diago_thr_init is 1.D-5.
- diago_full_acc is always .TRUE. .
- diago_rmm_conv is always .TRUE. .
         

The target Fermi energy (eV) of GC-SCF. One can start
with appropriate total charge of the system by giving tot_charge .
         

Convergence threshold of Fermi energy (eV) for GC-SCF.
         

Mixing factor for GC-SCF.
Larger values are recommended,
if systems with small DOS on Fermi surface as graphite.
         

Type of Van der Waals correction. Allowed values:
            

'grimme-d2', 'Grimme-D2', 'DFT-D', 'dft-d' :

Semiempirical Grimme's DFT-D2. Optional variables:
london_s6, london_rcut, london_c6, london_rvdw
S. Grimme, J. Comp. Chem. 27, 1787 (2006), doi:10.1002/jcc.20495
V. Barone et al., J. Comp. Chem. 30, 934 (2009), doi:10.1002/jcc.21112
            

'grimme-d3', 'Grimme-D3', 'DFT-D3', 'dft-d3' :

Semiempirical Grimme's DFT-D3. Optional variables:
dftd3_version, dftd3_threebody
S. Grimme et al, J. Chem. Phys 132, 154104 (2010), doi:10.1063/1.3382344
            

'TS', 'ts', 'ts-vdw', 'ts-vdW', 'tkatchenko-scheffler' :

Tkatchenko-Scheffler dispersion corrections with first-principle derived
C6 coefficients.
Optional variables: ts_vdw_econv_thr, ts_vdw_isolated
See A. Tkatchenko and M. Scheffler, PRL 102, 073005 (2009).
            

'MBD', 'mbd', 'many-body-dispersion', 'mbd_vdw' :

Many-body dipersion (MBD) correction to long-range interactions.
Optional variables: ts_vdw_isolated
A. Ambrosetti, A. M. Reilly, R. A. DiStasio, A. Tkatchenko, J. Chem. Phys. 140
18A508 (2014).
            

'XDM', 'xdm' :

Exchange-hole dipole-moment model. Optional variables: xdm_a1, xdm_a2
A. D. Becke et al., J. Chem. Phys. 127, 154108 (2007), doi:10.1063/1.2795701
A. Otero de la Roza et al., J. Chem. Phys. 136, 174109 (2012),
doi:10.1063/1.4705760
            

 Note that non-local functionals (eg vdw-DF) are NOT specified here but in input_dft
            

global scaling parameter for DFT-D. Default is good for PBE.
         

atomic C6 coefficient of each atom type

( if not specified default values from S. Grimme, J. Comp. Chem. 27, 1787 (2006),
  doi:10.1002/jcc.20495 are used; see file Modules/mm_dispersion.f90 )
         

atomic vdw radii of each atom type

( if not specified default values from S. Grimme, J. Comp. Chem. 27, 1787 (2006),
  doi:10.1002/jcc.20495 are used; see file Modules/mm_dispersion.f90 )
         

cutoff radius (a.u.) for dispersion interactions
         

Version of Grimme implementation of Grimme-D3:
            

dftd3_version = 2 :

Original Grimme-D2 parametrization
            

dftd3_version = 3 :

Grimme-D3 (zero damping)
            

dftd3_version = 4 :

Grimme-D3 (BJ damping)
            

dftd3_version = 5 :

Grimme-D3M (zero damping)
            

dftd3_version = 6 :

Grimme-D3M (BJ damping)
            

NOTE: not all functionals are parametrized.
            

Turn three-body terms in Grimme-D3 on. If .false. two-body contributions
only are computed, using two-body parameters of Grimme-D3.
If dftd3_version=2, three-body contribution is always disabled.
         

Optional: controls the convergence of the vdW energy (and forces). The default value
is a safe choice, likely too safe, but you do not gain much in increasing it
         

Optional: set it to .TRUE. when computing the Tkatchenko-Scheffler vdW energy or the
Many-Body dispersion (MBD) energy for an isolated (non-periodic) system.
         

Damping function parameter a1 (adimensional). It is NOT necessary to give
a value if the functional is one of B86bPBE, PW86PBE, PBE, BLYP. For functionals
in this list, the coefficients are given in:
   http://schooner.chem.dal.ca/wiki/XDM
   A. Otero de la Roza, E. R. Johnson, J. Chem. Phys. 138, 204109 (2013),
   doi:10.1063/1.4705760
         

Damping function parameter a2 (angstrom). It is NOT necessary to give
a value if the functional is one of B86bPBE, PW86PBE, PBE, BLYP. For functionals
in this list, the coefficients are given in:
   http://schooner.chem.dal.ca/wiki/XDM
   A. Otero de la Roza, E. R. Johnson, J. Chem. Phys. 138, 204109 (2013),
   doi:10.1063/1.4705760
         

The number of the space group of the crystal, as given
in the International Tables of Crystallography A (ITA).
This allows to give in input only the inequivalent atomic
positions. The positions of all the symmetry equivalent atoms
are calculated by the code. Used only when the atomic positions
are of type crystal_sg. See also uniqueb,
origin_choice, rhombohedral
         

Used only for monoclinic lattices. If .TRUE. the b
unique ibrav (-12 or -13) are used, and symmetry
equivalent positions are chosen assuming that the
twofold axis or the mirror normal is parallel to the
b axis. If .FALSE. it is parallel to the c axis.
         

Used only for space groups that in the ITA allow
the use of two different origins. origin_choice=1,
means the first origin, while origin_choice=2 is the
second origin.
         

Used only for rhombohedral space groups.
When .TRUE. the coordinates of the inequivalent atoms are
given with respect to the rhombohedral axes, when .FALSE.
the coordinates of the inequivalent atoms are given with
respect to the hexagonal axes. They are converted internally
to the rhombohedral axes and ibrav=5 is used in both cases.
         

variables used only if gate = .TRUE.

maximum number of iterations in a scf step
         

If .false. do not stop molecular dynamics or ionic relaxation
when electron_maxstep is reached. Use with care.
         

Convergence threshold for selfconsistency:
   estimated energy error < conv_thr
(note that conv_thr is extensive, like the total energy).

For non-self-consistent calculations, conv_thr is used
to set the default value of the threshold (ethr) for
iterative diagonalization: see diago_thr_init
         

If .TRUE. this turns on the use of an adaptive conv_thr for
the inner scf loops when using EXX.
         

When adaptive_thr = .TRUE. this is the convergence threshold
used for the first scf cycle.
         

When adaptive_thr = .TRUE. the convergence threshold for
each scf cycle is given by:
max( conv_thr, conv_thr_multi * dexx )
         

 Available options are:
            

'plain' :

 charge density Broyden mixing
            

'TF' :

as above, with simple Thomas-Fermi screening
(for highly homogeneous systems)
            

'local-TF' :

as above, with local-density-dependent TF screening
(for highly inhomogeneous systems)
            

mixing factor for self-consistency
         

number of iterations used in mixing scheme.
If you are tight with memory, you may reduce it to 4 or so.
         

For DFT+U : number of iterations with fixed ns ( ns is the
atomic density appearing in the Hubbard term ).
         

 Available options are:
            

'david' :

Davidson iterative diagonalization with overlap matrix
(default). Fast, may in some rare cases fail.
            

'cg' :

Conjugate-gradient-like band-by-band diagonalization.
MUCH slower than 'david' but uses less memory and is
(a little bit) more robust.
            

'ppcg' :

PPCG iterative diagonalization
            

'paro', 'ParO' :

ParO iterative diagonalization
            

'rmm-davidson', 'rmm-paro' :

RMM-DIIS iterative diagonalization.
To stabilize the SCF loop
RMM-DIIS is alternated with calls to Davidson or
ParO  solvers depending on the string used.
Other variables that can be used to tune the behavior of
RMM-DIIS are:  diago_rmm_ndim and diago_rmm_conv
            

Convergence threshold (ethr) for iterative diagonalization
(the check is on eigenvalue convergence).

For scf calculations: default is 1.D-2 if starting from a
superposition of atomic orbitals; 1.D-5 if starting from a
charge density. During self consistency the threshold
is automatically reduced (but never below 1.D-13) when
approaching convergence.

For non-scf calculations: default is (conv_thr/N elec)/10.
         

For conjugate gradient diagonalization:  max number of iterations
         

For ppcg diagonalization:  max number of iterations
         

For Davidson diagonalization: dimension of workspace
(number of wavefunction packets, at least 2 needed).
A larger value may yield a smaller number of iterations in
the algorithm but uses more memory and more CPU time in
subspace diagonalization (cdiaghg/rdiaghg). You may try
diago_david_ndim=4 if you are not tight on memory
and if the time spent in subspace diagonalization is small
compared to the time spent in h_psi
         

For RMM-DIIS diagonalization: dimension of workspace
(number of wavefunction packets, at least 2 needed).
         

If .TRUE., RMM-DIIS is performed up to converge.
If .FALSE., RMM-DIIS is performed only once.
         

For RMM-DIIS diagonalization:
blocking size of Gram-Schmidt orthogonalization
         

If .TRUE. all the empty states are diagonalized at the same level
of accuracy of the occupied ones. Otherwise the empty states are
diagonalized using a larger threshold (this should not affect
total energy, forces, and other ground-state properties).
         

Amplitude of the finite electric field (in Ry a.u.;
1 a.u. = 36.3609*10^10 V/m). Used only if lelfield==.TRUE.
and if k-points (K_POINTS card) are not automatic.
         

Finite electric field (in Ry a.u.=36.3609*10^10 V/m) in
cartesian axis. Used only if lelfield==.TRUE. and if
k-points (K_POINTS card) are automatic.
         

 Available options are:
            

'read' :

set the zero of the electronic polarization (with lelfield==.true..)
to the result of a previous calculation
            

'write' :

write on disk data on electronic polarization to be read in another
calculation
            

'none' :

none of the above points
            

 Available options are:
            

'atomic' :

starting potential from atomic charge superposition
(default for scf, *relax, *md)
            

'file' :

start from existing "charge-density.xml" file in the
directory specified by variables prefix and outdir
For nscf and bands calculation this is the default
and the only sensible possibility.
            

 Available options are:
            

'atomic' :

Start from superposition of atomic orbitals.
If not enough atomic orbitals are available,
fill with random numbers the remaining wfcs
The scf typically starts better with this option,
but in some high-symmetry cases one can "loose"
valence states, ending up in the wrong ground state.
            

'atomic+random' :

As above, plus a superimposed "randomization"
of atomic orbitals. Prevents the "loss" of states
mentioned above.
            

'random' :

Start from random wfcs. Slower start of scf but safe.
It may also reduce memory usage in conjunction with
diagonalization='cg'.
            

'file' :

Start from an existing wavefunction file in the
directory specified by variables prefix and outdir.
            

If .true., use a real-space algorithm for augmentation
charges of ultrasoft pseudopotentials and PAWsets.
Faster but numerically less accurate than the default
G-space algorithm. Use with care and after testing!
         

If .true., exploit real-space localization to compute
matrix elements for nonlocal projectors. Faster and in
principle better scaling than the default G-space algorithm,
but numerically less accurate, may lead to some loss of
translational invariance. Use with care and after testing!
         

 Available options are:
            

'default' :

if restarting, use atomic positions read from the
restart file; in all other cases, use atomic
positions from standard input.
            

'from_input' :

read atomic positions from standard input, even if restarting.
            

Initial ionic velocities. Available options are:
            

'default' :

start a new simulation from random thermalized
distribution of velocities if tempw is set,
with zero velocities otherwise; restart from
atomic velocities read from the restart file
            

'from_input' :

start or continue the simulation with atomic
velocities read from standard input - see card
ATOMIC_VELOCITIES
            

Specify the type of ionic dynamics.

For different type of calculation different possibilities are
allowed and different default values apply:

CASE ( calculation == 'relax' )
            

'bfgs' :

(default)  use BFGS quasi-newton algorithm,
based on the trust radius procedure,
for structural relaxation
            

'damp' :

use damped (quick-min Verlet)
dynamics for structural relaxation
Can be used for constrained
optimisation: see CONSTRAINTS card
            

'fire' :

use the FIRE minimization algorithm employing the
semi-implicit Euler integration scheme
see:
   Bitzek et al.,PRL, 97, 170201, (2006), doi: 10.1103/PhysRevLett.97.170201
   Guenole et al.,CMS, 175, 109584, (2020), doi: 10.1016/j.commatsci.2020.109584

Can be used for constrained
optimisation: see CONSTRAINTS card
            

CASE ( calculation == 'md' )
            

'verlet' :

(default)  use Verlet algorithm to integrate
Newton's equation. For constrained
dynamics, see CONSTRAINTS card
            

'langevin' :

ion dynamics is over-damped Langevin
            

'langevin-smc' :

over-damped Langevin with Smart Monte Carlo:
see R.J. Rossky, JCP, 69, 4628 (1978), doi:10.1063/1.436415
            

CASE ( calculation == 'vc-relax' )
            

'bfgs' :

(default)  use BFGS quasi-newton algorithm;
cell_dynamics must be 'bfgs' too
            

'damp' :

use damped (Beeman) dynamics for
structural relaxation
            

CASE ( calculation == 'vc-md' )
            

'beeman' :

(default)  use Beeman algorithm to integrate
Newton's equation
            

Used to extrapolate the potential from preceding ionic steps.
            

'none' :

 no extrapolation
            

'atomic' :

extrapolate the potential as if it was a sum of
atomic-like orbitals
            

'first_order' :

extrapolate the potential with first-order
formula
            

'second_order' :

as above, with second order formula
            

Note: 'first_order' and 'second-order' extrapolation make sense
only for molecular dynamics calculations
            

Used to extrapolate the wavefunctions from preceding ionic steps.
            

'none' :

 no extrapolation
            

'first_order' :

extrapolate the wave-functions with first-order formula.
            

'second_order' :

as above, with second order formula.
            

Note: 'first_order' and 'second-order' extrapolation make sense
only for molecular dynamics calculations
            

This keyword is useful when simulating the dynamics and/or the
thermodynamics of an isolated system. If set to true the total
torque of the internal forces is set to zero by adding new forces
that compensate the spurious interaction with the periodic
images. This allows for the use of smaller supercells.

BEWARE: since the potential energy is no longer consistent with
the forces (it still contains the spurious interaction with the
repeated images), the total energy is not conserved anymore.
However the dynamical and thermodynamical properties should be
in closer agreement with those of an isolated system.
Also the final energy of a structural relaxation will be higher,
but the relaxation itself should be faster.
         

variables used for molecular dynamics

keywords used only in BFGS calculations

keywords used only in the FIRE minimization algorithm

Specify the type of dynamics for the cell.
For different type of calculation different possibilities
are allowed and different default values apply:

CASE ( calculation == 'vc-relax' )
            

'none' :

 no dynamics
            

'sd' :

 steepest descent ( not implemented )
            

'damp-pr' :

damped (Beeman) dynamics of the Parrinello-Rahman extended lagrangian
            

'damp-w' :

damped (Beeman) dynamics of the new Wentzcovitch extended lagrangian
            

'bfgs' :

BFGS quasi-newton algorithm (default)
ion_dynamics must be 'bfgs' too
            

CASE ( calculation == 'vc-md' )
            

'none' :

 no dynamics
            

'pr' :

(Beeman) molecular dynamics of the Parrinello-Rahman extended lagrangian
            

'w' :

(Beeman) molecular dynamics of the new Wentzcovitch extended lagrangian
            

Target pressure [KBar] in a variable-cell md or relaxation run.
         

Fictitious cell mass [amu] for variable-cell simulations
(both 'vc-md' and 'vc-relax')
         

Used in the construction of the pseudopotential tables.
It should exceed the maximum linear contraction of the
cell during a simulation.
         

Convergence threshold on the pressure for variable cell
relaxation ('vc-relax' : note that the other convergence
            thresholds for ionic relaxation apply as well).
         

Select which of the cell parameters should be moved:
            

'all' :

 all axis and angles are moved
            

'ibrav' :

all axis and angles are moved,
               but the lattice remains consistent
               with the initial ibrav choice. You can use this option in combination
               with any other one by specifying "ibrav+option". Please note that some
               combinations do not make sense for some crystals and will guarantee that
               the relax will never converge. E.g. 'ibrav+2Dxy' is not a problem for
               hexagonal cells, but will never converge for cubic ones.
            

'a' :

 the x component of axis 1 (v1_x) is fixed
            

'b' :

 the y component of axis 2 (v2_y) is fixed
            

'c' :

 the z component of axis 3 (v3_z) is fixed
            

'fixa' :

 axis 1 (v1_x,v1_y,v1_z) is fixed
            

'fixb' :

 axis 2 (v2_x,v2_y,v2_z) is fixed
            

'fixc' :

 axis 3 (v3_x,v3_y,v3_z) is fixed
            

'x' :

 only the x component of axis 1 (v1_x) is moved
            

'y' :

 only the y component of axis 2 (v2_y) is moved
            

'z' :

 only the z component of axis 3 (v3_z) is moved
            

'xy' :

 only v1_x and v2_y are moved
            

'xz' :

 only v1_x and v3_z are moved
            

'yz' :

 only v2_y and v3_z are moved
            

'xyz' :

 only v1_x, v2_y, v3_z are moved
            

'shape' :

 all axis and angles, keeping the volume fixed
            

'volume' :

 the volume changes, keeping all angles fixed (i.e. only celldm(1) changes)
            

'2Dxy' :

 only x and y components are allowed to change
            

'2Dshape' :

 as above, keeping the area in xy plane fixed
            

'epitaxial_ab' :

 fix axis 1 and 2 while allowing axis 3 to move
            

'epitaxial_ac' :

 fix axis 1 and 3 while allowing axis 2 to move
            

'epitaxial_bc' :

 fix axis 2 and 3 while allowing axis 1 to move
            

BEWARE: if axis are not orthogonal, some of these options do not
        work (symmetry is broken). If you are not happy with them,
        edit subroutine init_dofree in file Modules/cell_base.f90
            

The target Fermi energy (eV). One can start
with appropriate total charge of the system by giving tot_charge .
         

Specify the type of dynamics for the Fictitious Charge Particle (FCP).

For different type of calculation different possibilities
are allowed and different default values apply:

CASE ( calculation == 'relax' )
            

'bfgs' :

(default) BFGS quasi-newton algorithm, coupling with ions relaxation
ion_dynamics must be 'bfgs' too
            

'newton' :

Newton-Raphson algorithm with DIIS
ion_dynamics must be 'damp' too
            

'damp' :

damped (quick-min Verlet) dynamics for FCP relaxation
ion_dynamics must be 'damp' too
            

'lm' :

Line-Minimization algorithm for FCP relaxation
ion_dynamics must be 'damp' too
            

CASE ( calculation == 'md' )
            

'velocity-verlet' :

(default) Velocity-Verlet algorithm to integrate Newton's equation.
ion_dynamics must be 'verlet' too
            

'verlet' :

Verlet algorithm to integrate Newton's equation.
ion_dynamics must be 'verlet' too
            

Convergence threshold on force (eV) for FCP relaxation.
         

Size of DIIS for FCP relaxation,
used only if fcp_dynamics = 'newton'.
         

Variables used for FCP dynamics.

If .TRUE., freeze all atoms
to perform relaxation or dynamics only with FCP.
         

The number of solvents (i.e. molecular species) in the unit cell
         

Specify the type of closure equation:
            

'kh' :

The Kovalenko and Hirata's model.
[A.Kovalenko, F.Hirata, JCP 110, 10095 (1999), doi:10.1063/1.478883]
            

'hnc' :

The HyperNetted-Chain model, which is
suitable only for solvents without charge.
[J.P.Hansen et al., Theory of simple liquids. Academic Press, London, 1990]
            

Temperature (Kelvin) of solvents.
         

Kinetic energy cutoff (Ry) for solvent's correlation functions.
If a solute is an isolated system or slab, you may allowed to
use default value. For a frameworked or porous solute (e.g. Zeolite, MOF),
it is desirable to apply a larger value. Solvents confined in a framework
often have a high frequency.
         

Specify the Lennard-Jones potential of solute on atomic type 'i':
            

'none' :

The Lennard-Jones potential is not specified here.
you must set solute_epsilon and solute_sigma.
            

'uff' :

Universal Force Field.
[A.K.Rappe et al., JACS 144, 10024 (1992), doi:10.1021/ja00051a040]
            

'clayff' :

Clay's Force Field
[R.T.Cygan et al., JPC B 108, 1255 (2004), doi:10.1021/jp0363287]
            

'opls-aa' :

OPLS-AA (generic parameters for QM/MM)
            

The Lennard-Jones potential of solute on atomic type 'i'.
Here, you can set the parameter 'epsilon' (kcal/mol).
         

The Lennard-Jones potential of solute on atomic type 'i'.
Here, you can set the parameter 'sigma' (Angstrom).
         

'zero' :

Starting correlation functions of 1D-RISM from zero.
( default for scf, *relax, *md )
            

'file' :

Start from existing "1d-rism_csvv_r.xml" file in the
directory specified by variables "prefix" and "outdir".
            

'fix' :

Read from existing "1d-rism_csvv_r.xml" file in the
directory specified by variables "prefix" and "outdir",
and never calculate 1D-RISM.
For nscf and bands calculation this is the default.
            

'zero' :

Starting correlation functions of 3D-RISM from zero.
( default for scf, *relax, *md )
            

'file' :

Start from existing "3d-rism_csuv_r.dat" file in the
directory specified by variables "prefix" and "outdir".
For nscf and bands calculation this is the default.
            

Coulomb smearing radius (a.u.) for 1D-RISM.
         

Coulomb smearing radius (a.u.) for 3D-RISM.
         

Maximum number of iterations in a 1D-RISM step.
         

Maximum number of iterations in a 3D-RISM step.
         

Convergence threshold for 1D-RISM.
         

Convergence threshold for 3D-RISM.
         

Size of Modified DIIS (MDIIS) for 1D-RISM.
         

Size of Modified DIIS (MDIIS) for 3D-RISM.
         

Step of Modified DIIS (MDIIS) for 1D-RISM.
         

Step of Modified DIIS (MDIIS) for 3D-RISM.
         

Gaussian width of bonds to smear intra-molecular correlation for 1D-RISM.
If 3D-RISM calculation, default is 0.
If Laue-RISM calculation, default is 2 / SQRT(ecutwfc).
         

Dielectric constant for 1D-RISM.
If rism1d_dielectric > 0, dielectrically consistent RISM (DRISM) is performed.

For details of DRISM, see:
J.S.Perkyns and B.M.Pettitt, CPL 1992, 190, 626, doi:10.1016/0009-2614(92)85201-K
         

Size of solvent molecules (a.u.) for 1D-RISM.
This is used only if rism1d_dielectric > 0.
If you have large molecules, you have to set ~ 20 a.u. .
         

Number of processes to calculate 1D-RISM.
         

Convergence level of 3D-RISM.
            

0.0 :

Convergence level is 'low'.
Convergence threshold of 3D-RISM is greater than
rism3d_conv_thr, when estimated energy error >> conv_thr .
The threshold becomes rism3d_conv_thr, when
estimated energy error is enough small.
            

0.0<x<1.0 :

Convergence level is 'medium'.
Convergence threshold of 3D-RISM is intermediate value
between 'low' and 'high', where rism3d_conv_level is mixing rate.
            

1.0 :

Convergence level is 'high'.
Convergence threshold of 3D-RISM is always rism3d_conv_thr .
            

If .TRUE., planar averages of solvent densities and potentials
are calculated and written to 'prefix.rism1'.
For 3D-RISM, default is .FALSE.
For Laue-RISM, default is .TRUE.
         

The number of z-grid points for the polynomial fit along the cell edge.
This is only for Laue-RISM.
         

If positive value, set the ending position offset [in a.u.]
of the solvent region on right-hand side of the unit cell,
measured relative to the unit cell edge.
(the solvent region ends at z = + [L_z/2 + laue_expand_right].)
This is only for Laue-RISM.
         

If positive value, set the ending position offset [in a.u.]
of the solvent region on left-hand side of the unit cell,
measured relative to the unit cell edge.
(the solvent region ends at z = - [L_z/2 + laue_expand_left].)
This is only for Laue-RISM.
         

Set the starting position [in a.u.] of the solvent region
on right-hand side of the unit cell. Then the solvent region is
defined as [ laue_starting_right , L_z/2 + laue_expand_right ],
where distribution functions are finite.
This is only for Laue-RISM.
         

Set the starting position [in a.u.] of the solvent region
on left-hand side of the unit cell. Then the solvent region is
defined as [ -L_z/2 - laue_expand_left , laue_starting_left ],
where distribution functions are finite.
This is only for Laue-RISM.
         

If positive value, set the buffering length [in a.u.]
of the solvent region on right-hand side of the unit cell.
Then correlation functions are defined inside of
[ laue_starting_right - laue_buffer_right , L_z/2 + laue_expand_right ].
This is only for Laue-RISM.
         

If positive value, set the buffering length [in a.u.]
of the solvent region on left-hand side of the unit cell.
Then correlation functions are defined inside of
[ -L_z/2 - laue_expand_left , laue_starting_left + laue_buffer_left ].
This is only for Laue-RISM.
         

If .TRUE., you can set different densities
to the solvent regions of right-hand side and left-hand side.
See SOLVENTS card.
         

Set the repulsive wall with (1/r)^12 term of Lennard-Jones potential.
This is only for Laue-RISM.
            

'none' :

The repulsive wall is not defined.
            

'auto' :

The repulsive wall is defined, whose edge position is set automatically.
One does not have to set laue_wall_z (the edge position).
            

'manual' :

The repulsive wall is defined, whose edge position is set manually.
One have to set laue_wall_z (the edge position).
            

Set the edge position [in a.u.] of the repulsive wall.
If laue_expand_right > 0.0, the repulsive wall is defined on [ -inf , laue_wall_z ].
If laue_expand_left > 0.0, the repulsive wall is defined on [ laue_wall_z , inf ].
This is only for Laue-RISM and laue_wall == 'manual' .
         

The density (1/bohr^3) of the repulsive wall.
This is only for Laue-RISM and laue_wall /= 'none' .
         

The Lennard-Jones potential of the repulsive wall.
Here, you can set the parameter 'epsilon' (kcal/mol).
This is only for Laue-RISM and laue_wall /= 'none' .
         

The Lennard-Jones potential of the repulsive wall.
Here, you can set the parameter 'sigma' (Angstrom).
This is only for Laue-RISM and laue_wall /= 'none' .
         

If .TRUE., the attractive term -(1/r)^6 of Lennard-Jones potential is added.
This is only for Laue-RISM and laue_wall /= 'none' .
         

Specified atomic positions will be IGNORED and those from the previous scf calculation will be used instead !!!

Syntax: ATOMIC_POSITIONS { alat | bohr | angstrom | crystal | crystal_sg }  X(1)   x(1)   y(1)   z(1)  {  if_pos(1)(1)   if_pos(2)(1)   if_pos(3)(1)  }  X(2)   x(2)   y(2)   z(2)  {  if_pos(1)(2)   if_pos(2)(2)   if_pos(3)(2)  }  . . .  X(nat)   x(nat)   y(nat)   z(nat)  {  if_pos(1)(nat)   if_pos(2)(nat)   if_pos(3)(nat)  }

Syntax: K_POINTS tpiba | crystal | tpiba_b | crystal_b | tpiba_c | crystal_c nks    xk_x(1)   xk_y(1)   xk_z(1)   wk(1)   xk_x(2)   xk_y(2)   xk_z(2)   wk(2)   . . .  xk_x(nks)   xk_y(nks)   xk_z(nks)   wk(nks)

Syntax: K_POINTS automatic nk1  nk2  nk3  sk1  sk2  sk3

Syntax: K_POINTS gamma

Syntax: SOLVENTS { 1/cell | mol/L | g/cm^3 }  X(1)   Density(1)   Molecule(1)   X(2)   Density(2)   Molecule(2)   . . .  X(nsolv)   Density(nsolv)   Molecule(nsolv)

Syntax: SOLVENTS { 1/cell | mol/L | g/cm^3 }  X(1)   Density_Left(1)   Density_Right(1)   Molecule(1)   X(2)   Density_Left(2)   Density_Right(2)   Molecule(2)   . . .  X(nsolv)   Density_Left(nsolv)   Density_Right(nsolv)   Molecule(nsolv)

Syntax: HUBBARD atomic | ortho-atomic | norm-atomic | wf | pseudo U  label(1)-manifold(1)  u_val(1)   [ J0  label(1)-manifold(1)  j0_val(1)   ] . . .   U  label(n)-manifold(n)  u_val(n)   [ J0  label(n)-manifold(n)  j0_val(n)   ]

Syntax: HUBBARD atomic | ortho-atomic | norm-atomic | wf | pseudo paramType(1)  label(1)-manifold(1)  paramValue(1)   . . .   paramType(n)  label(n)-manifold(n)  paramValue(n)

Syntax: HUBBARD atomic | ortho-atomic | norm-atomic | wf | pseudo U  label(I)-manifold(I)  u_val(I)   [ J0  label(I)-manifold(I)  j0_val(I)   ] V  label(I)-manifold(I)  label(J)-manifold(J)  I  J  v_val(I,J)   . . .   U  label(N)-manifold(N)  u_val(N)   [ J0  label(N)-manifold(N)  j0_val(N)   ] V  label(N)-manifold(N)  label(M)-manifold(M)  N  M  v_val(N,M)