Input File Description

Program: postahc.x / PHonon / Quantum ESPRESSO (version: 7.5)

TABLE OF CONTENTS

INTRODUCTION

&INPUT

prefix | outdir | ahc_dir | use_irr_q | ahc_nbnd | ahc_nbndskip | flvec | eta_eV | temp_kelvin | efermi_eV | amass_amu | ahc_win_min_eV | ahc_win_max_eV | skip_upper | skip_dw | adiabatic

INTRODUCTION

Purpose of postahc.x:

- Read the electron-phonon quantities calculated by ph.x with the
electron_phonon='ahc' option.

- Calculate the phonon-induced electron self-energy in the full matrix form
at a given temperature.

Structure of the input data:
========================================================================

&INPUT
   ...specs of namelist variables...
/
   

Namelist: &INPUT

prefix CHARACTER
Default: 'pwscf'
Prepended to input/output filenames; must be the same
used in the calculation of unperturbed system.
         
outdir CHARACTER
Default: value of the ESPRESSO_TMPDIR environment variable if set;
current directory ('./') otherwise
Directory containing input, output, and scratch files;
must be the same as specified in the calculation of
the unperturbed system.
         
ahc_dir CHARACTER
Status: REQUIRED
Directory where the binary files are located.
         
use_irr_q LOGICAL
Default: .false.
If .true., assume that the q points are on the irreducible grid. In this case,
the data in ahc_dir must have been actually generated from a calculation
on an irreducible q grid.
Off-diagonal self-energies cannot be computed if use_irr_q = .true.
         
ahc_nbnd INTEGER
Status: REQUIRED
Number of bands for which the electron self-energy is to be computed. Must be
identical to ahc_nbnd of the ph.x run with electron_phonon='ahc'.
         
ahc_nbndskip INTEGER
Default: 0
Number of bands to exclude when computing the self-energy. Must be identical to
ahc_nbndskip of the ph.x run with electron_phonon='ahc'.
         
flvec CHARACTER
Status: REQUIRED
File containing the normalized phonon displacements written by matdyn.x.
         
eta_eV REAL
Status: REQUIRED
Magnitude of the small imaginary component included to smooth the energy
denominators, in eV.
         
temp_kelvin REAL
Status: REQUIRED
Temperature in Kelvins at which the electron self-energy is calculated.
         
efermi_eV REAL
Status: REQUIRED
Fermi energy of the electrons in eV.
         
amass_amu(i), i=1,ntyp REAL
Status: REQUIRED
Mass for each atom type in atomic mass unit.
         
ahc_win_min_eV REAL
Default: -1.d8
Lower bound of active AHC window for the lower Fan term in eV.
         
ahc_win_max_eV REAL
Default: 1.d8
Upper bound of active AHC window for the lower Fan term in eV.
         
skip_upper LOGICAL
Default: .false.
If .true., skip calculation of the upper Fan self-energy. Also, truncate the
Debye-Waller self-energy to include only the low-energy band contribution.
(Corresponds to the second term (lower Fan + lower DW) of Eq. (G1-revised) of
J.-M. Lihm and C.-H. Park, PRX 12, 039901(E) (2022).)
If .false., calculate the contribution of both the high-energy and low-energy
bands. In this case, ahc_upfan_iq#.bin files must be present in ahc_dir.
         
skip_dw LOGICAL
Default: .false.
If .true., skip calculation of the Debye-Waller self-energy.
If .false., ahc_dw.bin file must be present in ahc_dir.
         
adiabatic LOGICAL
Default: .false.
If .true., use the adiabatic approximation when computing the Fan self-energy
by ignoring the phonon frequency in the denominator. This approximation is known
to be inaccurate and even divergent in some materials (S. Poncé et al., J. Chem.
Phys. 143, 102813 (2015)). Therefore, this keyword should be used only for
experimental or debugging purposes.
         
This file has been created by helpdoc utility on Wed Sep 03 14:23:33 CEST 2025.