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4.9 WHAT='PLOT_BZ'

With this option the code writes a script to make a plot of the Brillouin zone (BZ) and of the path (the default one or the one given in input). The script must be read by the asymptote code, available at http://asymptote.sourceforge. net/. In many Linux distributions this code is available as a separate package, but it is not installed by default.
The following variables control the plot:
lasymptote  : if .TRUE. asymptote is called from within the pro-
              gram and the pdf file with a plot of the BZ is 
              produced
              Default: logical .FALSE.
flasy       : initial part of the name of the file where the 
              asymptote script is written and of the name of the 
              pdf file.
              Default: character(len=*) 'asy_tmp'
asymptote_command  : the command that invokes asymptote and 
              produces the pdf file of the BZ.
              Default: character(len=*) 'asy -f pdf -noprc 
              flasy.asy'
npx         : used only in the monoclinic cell, this parameter 
              is needed to determine the shape of the Brillouin 
              zone. The default value is usually large enough, 
              but for particular shapes of the monoclinic 
              Brillouin zone it could be small. If the code 
              stops with an error asking to increase npx, double 
              it until the error disappears.
              Default: integer 8

Starting from version 1.5.0 thermo_pw writes also a script to plot the BZ using the freeCAD software. In order to plot the BZ you need to download the code (from the site https://www.freecadweb.org/, version 0.18 or higher) and, after opening it, choose Macro/Macros to execute the freeCAD macro that you find in the working directory (the default name is tpw_freecad. FCMacro). In the Doc directory there is a file called tpw_bz.svg that contains the template for the PDF file with the BZ plot. This file should be copied in the directory where you run the freeCAD executable before running the script. In the same directory there is a file called brillouin_view.cam in the Doc directory that can be used with the option View/Freeze Display to obtain the standard view of the Brillouin zone. This feature is still experimental.
The following variables control the plot:

fcfact      : factor used to convert from the 2\pi/a units used 
              for the Brillouin zone plot to the millimeters 
              units needed to make a plot in freecad. 
              Default: real 100.0
fc_red,     
fc_green,
fc_blue     : color of the BZ in the rgb format (between 0.0 
              and 1.0). By default the BZ will be yellow.
              Default: real 1.0, 1.0, 0.0
fc_transparency : transparency of the BZ between 0 (opaque) 
              and 100 (transparent).
              Default: integer 15.
freecadfile : name of the file that contains the freecad 
              script to plot the Brillouin zone.
              Default: character(len=*) 'tpw_freecad'
The structure of the solid can be seen using the XCrySDen code that can read the input file of pw.x. You can find the code at http://www.xcrysden.org/. thermo_pw produces also a file in the xsf format called prefix.xsf, where the variable prefix is given in the input of pw.x. This can be useful when the nonequivalent atomic positions and the space group are given in the input of pw.x. To see an xsf file, give the command xcrysden -xsf file.xsf.

With this option the code produces also a file with the X-ray powder diffraction intensities for the solid. A plot shows the scattering angles and the relative intensity of each peak. Note that this plot is made using a superposition of atomic charges, not the self-consistent charge. By setting the flag lformf=.TRUE. the atomic form factors of all the atomic types used to calculate the intensities are plotted. By setting the flag lxrdp=.TRUE. the intensities plot is done also after the cell optimization and after a self-consistent calculation for the options that support it. The variables that control these plots are:

lambda      : The X-ray wavelength (in A) used to calculate the 
              scattering angles.
              Default: Cu alpha line 1.541838 A if lambda_element 
              is empty
lambda_elem : The anode element, used to set the X-ray 
              wavelength. Supported elements 'Cr', 'Fe', 'Co', 
              'Cu', 'Mo'. NB: lambda must be zero to use 
              lambda_elem, otherwise the value of lambda given 
              in input is used.
              Default: character(len=2) ' ' 
flxrdp      : name of the file where the scattering angles and 
              intensities are written.
              Default: character 'output_xrdp.dat'
flpsxrdp    : name of the postscript file with the X-ray 
              diffraction spectrum.
              Defaults: character 'output_xrdp'
lxrdp       : if .TRUE. compute the xrdp also after the cell 
              optimization with all the options mur_lc_... 
              with the uniformly strained atomic positions 
              and after the scf calculation if supported by 
              the option. 
              Default: logical .FALSE.
lformf      : if .TRUE. plot also the form factor of each 
              atom type present in the solid. Note that the 
              atom type is recognized from the atom name in 
              the thermo_pw input. The name must coincide 
              with the symbols in the periodic table. (Cu, H, 
              Li, Li1, ... are correct, CU, LI, H1 ...  are 
              wrong).
              Default: logical .FALSE.
smin        : minimum value of s used in the atomic form 
              factor plot.
              Default: real 0.0
smax        : maximum value of s used in the atomic form 
              factor plot.
              Default: real 1.0
nspoint     : number of points in which the atomic form 
              factor is calculated.
              Default: integer 200
lcm         : when .TRUE. the code uses the Cromer-Mann 
              coefficients form the International Tables of 
              Crystallography to compute the atomic form 
              factors, otherwise uses the Doyle-Turner or 
              Smith-Burge parameters.
              Default: logical .FALSE.
flformf     : name of the file in which the atomic form 
              factor is written. The code adds a number to 
              each file name and creates a file per atom type.
              Defaults: character 'output_formf.dat'
flpsformf   : name of the postscript file with the atomic 
              form factor. The code adds a number to each 
              file name and creates a file per atom type.
              Defaults: character 'output_formf'


next up previous contents
Next: 4.10 WHAT='SCF_PH' Up: 4 Input variables Previous: 4.8 WHAT='SCF_DOS'   Contents
2021-07-20