sumo-optplot

sumo-optplot is a program for generating publication-ready optical absorption spectra diagrams from VASP calculations. The script supports plotting multiple spectra simultaneously.

Usage

The full range of options supported by sumo-optplot are detailed in the Command-Line Interface section, and be can be accessed using the command:

sumo-optplot -h

To plot an absorption spectra, simply run the following command in a folder containing a vasprun.xml or vasprun.xml.gz file, which has been calculated using LOPTICS = .TRUE.:

sumo-optplot

The plot will be written to a file named absorption.pdf, with the raw data written to absorption.dat.

For example, if we run the command in the sumo/tests/data/Cs2SnI6/optics directory, the absorption spectra should look like:

_images/absorption_basic.png

Basic Options

sumo-optplot automatically searches for a vasprun.xml file in the current directory. To specify a particular vasprun.xml to plot, the --filenames option can be used.

The height, and width of the graphic, along with the y-axis limits, can be controlled via the --width, --height, --ymax, and --ymin options.

Additional gaussian broadening can be applied using the --gaussian option. The setting expects a floating point number as the argument and controls the standard deviation of the broadening applied.

Anisotropic Absorption

By default, sumo-optplot plots the average optical absorption. The anisotropic contributions from the x, y and z cartesian directions can be plotted individually using the --anisotropic option.

For example, if we run the following command in the sumo/tests/data/Cs2SnI6/optics directory, the anisotropic absorption spectra should look like:

sumo-optplot --anisotropic
_images/absorption_anisotropic.png

Displaying Band Gaps

The band gap of the system can be indicated using the --bandgap option. There are several ways to use this option:

  • If the option is given with no arguments, then the band gap will be extracted from the vasprun.xml file.

  • A path to a separate vasprun.xml file can be supplied, in which case the band gap will be read from this calculation.

  • A number can be supplied.

For example, if we run the following command in the sumo/tests/data/Cs2SnI6/optics directory, the plot should look like:

sumo-optplot --bandgap ../bandstructure/split-01/vasprun.xml.gz
_images/absorption_bandgap.png

Plotting Multiple Spectra

Multiple absorption spectra can be plotted simultaneously by specifying multiple vasprun.xml files using the --filenames option. A label will be generated for each system, based on the composition. Alternatively, the --labels option can be used to provide a name for each system. The number of vasprun.xml files must be equivalent for the number of labels.

For example, if we run the following command in the sumo/tests/data/Cs2SnI6/optics directory, the plot should look like:

sumo-optplot --filenames vasprun.xml.gz ../../Cs2SnBr6/vasprun.xml.gz
_images/absorption_multi.png

This mode also supports plotting the band gap of each compound using the --bandgap option.

Questaal

LMTO optics calculations with the lmf program are supported; when OPTICS MODE=1 (or greater) in the ctrl.ext file an opt.ext file is written with the imaginary dielectric function vs energy in Ry. Sumo can import this file and compute a real component with the Kramers-Kronig relation; this provides the information needed for plotting optical properties. To plot the optical absorption:

sumo-optplot --code questaal -f opt.ext

The opt_BSE.out file from bethesalpeter calculations is also supported; this format will be detected as long as “opt_BSE” is somewhere in the filename.

Command-Line Interface

optplot is a script to produce optical absorption spectra diagrams

usage: sumo-optplot [-h] [-f F [F ...]] [-p P] [-d D] [-c C [C ...]] [-g G]
                    [-b [E ...]] [-l L [L ...]] [-a] [--height HEIGHT]
                    [--width WIDTH] [--xmin XMIN] [--xmax XMAX]
                    [--ymin YMIN [YMIN ...]] [--ymax YMAX [YMAX ...]]
                    [--style STYLE [STYLE ...]] [--no-base-style]
                    [--format FORMAT] [--dpi DPI] [--font FONT]
                    [--units UNITS]
                    [M ...]

Positional Arguments

M

Possible choices: loss, n_imag, eps_imag, eps_real, absorption, n_real

Optical properties to plot. Multiple choices will be displayed as subplots. Accepted values: “absorption” (optical absorption over distance), “loss” (energy-loss function -Im(1/eps)), “eps_real” and “eps_imag” (real and imaginary parts of the dielectric function), “n_real” (real part of complex refractive index)”n_imag” (imaginary part of RI, also known as the extinction coefficient kappa.)

Default: “absorption”

Named Arguments

-f, --filenames

path to one or more vasprun.xml files

-p, --prefix

prefix for the files generated

-d, --directory

output directory for files

-c, --code

Original calculator. Accepted values are “vasp” and “questaal”.

Default: “vasp”

-g, --gaussian

standard deviation of gaussian broadening

-b, --bandgaps

indicate the fundamental band gap (options: nothing, vasprun.xml file, or float). A sequence of files and values may be provided, corresponding to the optical data files. To skip a line, set a value outside the plot range (e.g. -1).

-l, --labels

labels for the absorption specta

-a, --anisotropic

separate spectra into to x, y, and z directions

Default: True

--height

height of the graph

--width

width of the graph

--xmin

minimum energy on the x-axis

Default: 0.0

--xmax

maximum energy on the x-axis

--ymin

minimum intensity on the y-axis; may specify multiple values if plotting more than one axis. Use “auto” or “_” for automatic value.

Default: [‘auto’]

--ymax

maximum intensity on the y-axis; may specifymultiple values if plotting more than one axis. Use “auto” or “_” for automatic value.

Default: [‘auto’]

--style

matplotlib style specifications

--no-base-style

prevent use of sumo base style

Default: False

--format

image file format (options: pdf, svg, jpg, png)

Default: “pdf”

--dpi

pixel density for image file

Default: 400

--font

font to use

--units

x-axis units (options: eV or nm)

Default: “eV”

Author: Alex Ganose Version: 1.0 Last updated: Jan 10, 2018