3.1 Structure of the PHonon package

PHonon has the following directory structure, contained in a subdirectory PHonon/ of the main QUANTUM ESPRESSO tree:

Doc/	: contains the user_guide and input data description
examples/	: some running examples
PH/	: source files for phonon calculations and analysis
Gamma/	: source files for Gamma-only phonon calculation
FD/	: source files for FInite-Difference calculations

Important Notice: since v.5.4, many modules and routines that were common to all linear-response QUANTUM ESPRESSO codes are moved into the new LR_Modules subdirectory of the main tree. Since v.6.0, the D3 code for anharmonic force constant calculations has been superseded by the D3Q code, available on https://sourceforge.net/projects/d3q/ and automatically downloadable from QUANTUM ESPRESSO.

The codes available in the PHonon package can perform the following types of calculations:

• phonon frequencies and eigenvectors at a generic wave vector, using Density-Functional Perturbation Theory;
• effective charges and dielectric tensors;
• electron-phonon interaction coefficients for metals;
• interatomic force constants in real space;
• Infrared and Raman (nonresonant) cross section.

Note: since v.5.4, packages PlotPhon (for phonon plotting) and QHA (vibrational free energy in the Quasi-Harmonic approximations), contribute by the late Prof. Eyvaz Isaev, are no longer bundled with PHonon. Their latest version can be found in the tarballs of v.5.3 of QE.