*** FILE AUTOMATICALLY CREATED: DO NOT EDIT, CHANGES WILL BE LOST *** ------------------------------------------------------------------------ INPUT FILE DESCRIPTION Program: band_interpolation.x / PWscf / Quantum ESPRESSO (version: 7.5) ------------------------------------------------------------------------ Purpose of band_interpolation.x: This contains four band energies interpolation methods, to be advantageously (but not necessarly) used for EXX band structure computations. The PP/src/band_interpolation.x post-processing subprogram reads the band energies stored in the pwscf.xml file after an SCF calculation on a uniform Monkhorst-Pack grid, and interpolates the eigenvalues to an arbitrary set of k-points provided in input. The workflow is just: (1) do an SCF on a uniform grid (2) call the interpolator from the folder in which the pwscf.xml file is present (band_interpolation.x < input) For large EXX calculations the first step can be splitted in two substeps: (1) do an SCF calculation on a uniform grid with occupied bands only (2) do a NSCF (or Bands) calculation on the same uniform grid adding virtual orbitals (3) call the interpolator from the folder in which the pwscf.xml file is present Four interpolation methods have been included (see "method"). The interpolated band structure in eV units is written in a file named [method].dat (e.g. fourier-diff.dat for the fourier-diff method) that is plottable with Grace or Gnuplot (e.g. xmgrace -nxy fourier-diff.dat) Structure of the input data: ============================ &INTERPOLATION ... / [ ROUGHNESS RoughN 'automatic' or RoughC(1) RoughC(2) RoughC(3) ... RoughC(RoughN) ] [ USER_STARS NUser vec_X vec_Y vec_Z ] K_POINTS { tpiba_b } nks xk_x, xk_y, xk_z, wk ======================================================================== NAMELIST: &INTERPOLATION +-------------------------------------------------------------------- Variable: method Type: CHARACTER Default: 'fourier-diff' Description: The interpolation method to be used Description: Available options are: 'fourier-diff' : band energies, as functions of k, are expanded in reciprocal space using a Star function basis set (algorithm from Pickett W. E., Krakauer H., Allen P. B., Phys. Rev. B, vol. 38, issue 4, page 2721, 1988, https://link.aps.org/doi/10.1103/PhysRevB.38.2721 ). WARNING: The pwscf.xml file must be generated with "nosym" == .false. . 'fourier' : band energies, as functions of k, are expanded in reciprocal space using a Star function basis set (algorithm from D. D. Koelling, J. H. Wood, J. Comput. Phys., 67, 253-262 (1986). https://ui.adsabs.harvard.edu/abs/1986JCoPh..67..253K ). WARNING: The pwscf.xml file must be generated with "nosym" == .false. . 'idw' : inverse distance weighting interpolation with Shepard metric (ACM 68: Proceedings of the 1968 23rd ACM national conference, January 1968, Pages 517–524, https://doi.org/10.1145/800186.810616 ). WARNING: The pwscf.xml file must be generated with "nosym" == .true. . WARNING: This method is REALLY simple and provides only a very rough estimate of the band structure. 'idw-sphere' : inverse distance weighting interpolation inside a sphere of given radius. WARNING: The pwscf.xml file must be generated with "nosym" == .true. . WARNING: This method is REALLY simple and provides only a very rough estimate of the band structure. +-------------------------------------------------------------------- +-------------------------------------------------------------------- Variable: miller_max Type: INTEGER Default: 6 Description: The maximum Miller index used to automatically generate the set of symmetry inequivalent Star vectors (only for "method" == 'fourier-diff' or 'fourier') +-------------------------------------------------------------------- +-------------------------------------------------------------------- Variable: check_periodicity Type: LOGICAL Default: .FALSE. Description: If .TRUE. a (time consuming) step is performed, to check whether all the Star functions have the correct lattice periodicity (only for "method" == 'fourier-diff' or 'fourier') . For automatically generated Star functions this should never occur by construction, and the program will stop and exit in case one Star function with wrong periodicity is found (useful for debugging and program sanity check). If additional user-defined Star vectors are specified (see optional card "USER_STARS"), the program will print a WARNING in case one Star function with wrong periodicity is found. +-------------------------------------------------------------------- +-------------------------------------------------------------------- Variable: p_metric Type: INTEGER Default: 2 Description: The exponent of the distance in the IDW method ( only for "method" == 'idw' or 'idw-sphere') +-------------------------------------------------------------------- +-------------------------------------------------------------------- Variable: scale_sphere Type: INTEGER Default: 4.0d0 Description: The search radius for "method" == 'idw-sphere', is Rmin * scale_sphere, where Rmin is the minimum distance found between the uniform grid of k-points. If scale_sphere is too small, some k-points of the path might not see enough uniform grid points to average energies, whereas for large values the method becomes equal to "method" == 'idw'. +-------------------------------------------------------------------- ===END OF NAMELIST====================================================== ======================================================================== CARD: ROUGHNESS OPTIONAL CARD, USED ONLY IF "METHOD" == 'FOURIER-DIFF', OR 'FOURIER', IGNORED OTHERWISE! This card can be used to change the roughness functional that is minimized in the "method" == 'fourier-diff' and 'fourier'. In case "method" == 'fourier-diff', or 'fourier' and card ROUGHNESS is not specified the default roughness will be used with "RoughN" == 1 and "RoughC"(1) == 1.0d0. ///////////////////////////////////////// // Syntax: // ///////////////////////////////////////// ROUGHNESS RoughN RoughC(1) RoughC(2) . . . RoughC(RoughN) ///////////////////////////////////////// DESCRIPTION OF ITEMS: +-------------------------------------------------------------------- Variable: RoughN Type: INTEGER Default: 1 Description: Number of terms included in the roughness functional +-------------------------------------------------------------------- +-------------------------------------------------------------------- Variables: RoughC Type: REAL Default: 1.0d0 Description: Coefficients for the terms included in the roughness functional. They can be explicitely given or 'automatic' can be specified instead of numbers to use default coefficients. +-------------------------------------------------------------------- ===END OF CARD========================================================== ======================================================================== CARD: USER_STARS OPTIONAL CARD, USED ONLY IF "METHOD" == 'FOURIER-DIFF', OR 'FOURIER', IGNORED OTHERWISE ! ///////////////////////////////////////// // Syntax: // ///////////////////////////////////////// USER_STARS NUser vec_x(1) vec_y(1) vec_z(1) vec_x(2) vec_y(2) vec_z(2) . . . vec_x(NUser) vec_y(NUser) vec_z(NUser) ///////////////////////////////////////// DESCRIPTION OF ITEMS: +-------------------------------------------------------------------- Variable: NUser Type: INTEGER Default: 0 Description: Number of supplied additional Star vectors. +-------------------------------------------------------------------- +-------------------------------------------------------------------- Variables: vec_x, vec_y, vec_z Type: REAL Description: Additional user-defined Star vectors that are added to the automatically generated ones to augment the Star functions basis set. You might also want to check "check_periodicity" when providing user-defined Star vectors. +-------------------------------------------------------------------- ===END OF CARD========================================================== ======================================================================== CARD: K_POINTS { tpiba_b } ________________________________________________________________________ * IF tpiba_b : ///////////////////////////////////////// // Syntax: // ///////////////////////////////////////// K_POINTS tpiba_b 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) ///////////////////////////////////////// ENDIF ________________________________________________________________________ DESCRIPTION OF ITEMS: +-------------------------------------------------------------------- Card's flags: { tpiba_b } Default: none Description: All K_POINTS options other than tpiba_b have been disabled in the interpolation. tpiba_b : Used for band-structure plots. See Doc/brillouin_zones.pdf for usage of BZ labels; otherwise, k-points are in units of 2 pi/a. nks points specify nks-1 lines in reciprocal space. Every couple of points identifies the initial and final point of a line. pw.x generates N intermediate points of the line where N is the weight of the first point. +-------------------------------------------------------------------- +-------------------------------------------------------------------- Variable: nks Type: INTEGER Description: Number of supplied special k-points. +-------------------------------------------------------------------- +-------------------------------------------------------------------- Variables: xk_x, xk_y, xk_z, wk Type: REAL Description: Special k-points (xk_x/y/z) in the irreducible Brillouin Zone (IBZ) of the lattice (with all symmetries) and weights (wk) See the literature for lists of special points and the corresponding weights. If the symmetry is lower than the full symmetry of the lattice, additional points with appropriate weights are generated. Notice that such procedure assumes that ONLY k-points in the IBZ are provided in input +-------------------------------------------------------------------- ===END OF CARD========================================================== This file has been created by helpdoc utility on Wed Sep 03 14:28:58 CEST 2025