Input File Description

Prepended to input/output filenames; must be the same
used in the previous PW calculations.
         

Directory containing input, output, and scratch files;
must be the same as specified in the calculation of
previous PW calculation.
         

Specify the KCW calculation to be done
Possible choices:
            

'wann2kcw' :

Pre-processing to prepare KCW calculation.
Read previous PWSCF and possibly W90 outputs and prepare the KCW
calculation
            

'screen' :

Perform the calculation of KCW screening coefficient using a
LR approach as described here https://doi.org/10.1021/acs.jctc.7b01116
and arXiv:2202.08155
            

'ham' :

Perform the calculation interpolation and diagonalization of the KI hamiltonian
            

'cc' :

Computes the (estimated) q+G=0 contribution to the bare and screened KC corrections.
A report on this quantities is printed on output and can be used to correct a
posteriori a "screen" calculation performed without any corrective scheme (l_vcut=.false.)
avoiding the need of re-doing a "screen" calculation.
            

= 0 : minimal output
= 1 : as above + performs additional checks.
> 1 : as above + additional infos on all the steps.
         

If true the KS canonical orbitals are used instead of Wannier
functions. It makes sense for isolated system only.
         

If true read the Unitary matrix written by Wannier90.
Implicitely means a previous wannier90 calculation was
performed and a KCW calculation will be performed starting
from MLWF. Requires 'write_hr = .true.' in wannier90.
         

HARD-CODED FOR NOW. Two or more Wannier functions are considered
identical if their spread (self-hartree) differ by less than spread_thr.
Requires check_spread = .true.
         

If kcw_at_ks = .TRUE. only the screening paramenter for the HOMO is
calculated. Mainly for a perturbative calculation of the first Ionization
Potential in isolated systems.
         

If .TRUE. the Gygi-Baldereschi scheme is used to deal with
the q->0 divergence of the Coulomb integral (bare and screened).
Improves the convergence wrt k/q-point sampling.
Requires to correctly set eps_inf for the calculation of
the screened interaction.

Use it only for periodic system.
For isoleted system use assume_isolated, instead.
         

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.
            

'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.
            

Which spin channel to calculate (only collinear calculation).
1 = spin up channel
2 = spin down channel
It has to be consistent with the previous Wannier90
calculation (see 'spin' keyword in Wannier90 documentation)
         

Parameters of the Monkhorst-Pack grid (no offset).
Same meaning as for nk1, nk2, nk3 in the input of pw.x.
It has to coincide with the regular mesh used for the
wannier90 calculation.
         

If .true. the response function is computed neglecting xc
effects both in the kernel and in the response function (RPA).
         

The seedname of the previous Wannier90 calculation for occupied states.
NOTA BENE: the code implicitely assumed that the seedname for empty
state is the same as that for occupied state with "_emp" appended.
Keep this in mind when set up the wannier90 inputs.

For example:
wann.win         is the wannier90 input file for the occupied states.
wann_emp.win     is the wannier90 input file for the empty states.
         

The number of wannier function for the occupied manifold.
It has to coincide with the number of occupied KS orbitals.
The whole KS manifold has to be wannierised (no 'exclude_band'
option for occupied state, at the moment).
         

The number of wannier function for the empty manifold.
It has to coincide with the number of empty wannier function
from the previous wannier90 calculation
         

If true empty state are computed. Require a previous wannier90
calculation for the empty manifold. The code search for the
unitary matrices in the wannier90 file seedname_emp_u.mat
         

Specify if a disentangle unitary matrix needs to be read. Requires
a consisten calcuation from the previous wannier90 run.
         

Specify if a diagonalization of the KS matrix build using the wannier
function in input has to be performed. This is mainly for debugging purpose.
         

Maximum number of iterations in a scf step. If you want
more than 100, edit variable "maxter" in PH/phcom.f90
         

 Number of iterations used in potential mixing.
         

 Threshold for self-consistency.
         

Perform the screening calculation for a particular orbital.
If i_orb = -1 (default) all the orbitals are computed.
Assumes values between 1 and the total number of wannier
functions.
         

The macroscopic dielectric constant. Needed for the Gygi-Baldereschi
scheme if l_vcut = .TRUE.
Typically from exp or from a ph.x calculation.

NOTA BENE: This would be equivalent to a Makov-Payne correction. It works well
for cubic systems. Less well for anisotropic systems.

ANISOTROPIC SYSTEMS: In this case a generalization of the GB scheme is implemented
based on Nano Lett.,9, 975 (2009). It requires the full dielectric tensor to be provided.
The code searches (in the working dir) for a file named "eps.dat" containing the macrospocic
dielectric tensor. If it does not find it, the value eps_inf provided in input will be
used (isotropic approximation). If not even eps_inf is provided in input no correction
is applied to the screened KC correction.
         

If .TRUE. the spread (self-hartree) of the Wannier functions is
checked and used to decide whether two or more Wannier functions
can be considered "identical" or not. Two Wannier functions are
considered identical if their spread (self-hartree) differ by less
than 1e-4 Ry (Hard coded for now, see spread_thr).
         

If .true. the interpolated band structure is computed along
a path secified with the K_POINTS card ( see PW documentation
https://www.quantum-espresso.org/Doc/INPUT_PW.html#idm1487 )
         

If .true. the position of the Wannier function inside the cell is used
to set the proper distance and to have a smoother interpolation. Requires
seedname_centres.xyz to be printed by the previous Wannier90 run. If the
file is not found it is automatically switched to .FALSE. and only the
distance between the cells is used (see also Wannier90 documentation)
         

If .true. the KCW hamiltonain in the Wannier basis and in real spase H(R)_m_n
is printed to file. Usefull for furhter post-processing.
         

If .true. only the on-site and diagonal elements of the KCW hamiltonain
are computed (R=0 and n=m).