Example of kpath_generator

In order to plot a band structure, one must define a set of \(k\)-points following a desired \(k\)-path in momentum space. PyProcar’s \(k\)-path generation utility enables a the user to automatically generate a suitable and sufficient \(k\)-path given the crystal structure, typically read from the POSCAR file (VASP).

General Format

pyprocar.kpath(infile, outfile, grid-size, with-time-reversal, recipe, threshold, symprec, angle-tolerance,supercell_matrix)

First download the example files with the code below. Then replace data_dir below.

Downloading example

 data_dir = pyprocar.download_example(save_dir='',
                             material='Fe',
                             code='vasp',
                             spin_calc_type='non-spin-polarized',
                             calc_type='bands')

This information is automatically written to a KPOINTS file. The retrieved \(k\)-path can be used for other DFT codes with slight modifications.

More details regarding these parameters can be found in the SeeK-path manual. The \(k\)-path generation utility within PyProcar is based on the Python library seekpath developed by Hinuma et al:

Y. Hinuma, G. Pizzi, Y. Kumagai, F. Oba, I. Tanaka, Band structure diagram paths based on crystallography, Computational Materials Science 128 (2017) 140–184.doi:10.1016/j.commatsci.2016.10.015.

# sphinx_gallery_thumbnail_number = 1

Plotting K Path

import pyvista
# You do not need this. This is to ensure an image is rendered off screen when generating exmaple gallery.
pyvista.OFF_SCREEN = True

importing pyprocar and specifying local data_dir

import os
import numpy as np
import pyprocar



data_dir = f"{pyprocar.utils.ROOT}{os.sep}data{os.sep}examples{os.sep}Fe{os.sep}vasp{os.sep}spin-polarized-colinear{os.sep}bands"
poscar = f"{data_dir}{os.sep}POSCAR"

k_path, k_labels = pyprocar.kpath(poscar,'KPOINTS',40,True,'hpkot',1e-07,1e-05,-1.0,np.eye(3))


# Getting unique points for plotting
unique_labels = []
unique_kpath= []
for i,k_label in enumerate(k_labels):
    if k_label not in  unique_labels:
        unique_labels.append(k_label)
        unique_kpath.append(k_path[i])


plotter=pyvista.Plotter()

# plotting connecting lines
for ik,points in enumerate(k_path):
    if ik == len(k_path) - 1:
        plotter.add_lines(np.array([k_path[ik-1],k_path[ik]]), color='red', width = 10)
    else:
        plotter.add_lines(np.array([k_path[ik],k_path[ik+1]]), color='red', width = 10 )

# plotting points and labels
plotter.add_point_labels(unique_kpath, unique_labels, point_color = 'blue', text_color='blue', render_points_as_spheres=True, point_size=20, font_size=36, always_visible=True)
plotter.show_axes()
plotter.show_grid()
plotter.view_yz()
plotter.show()

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A Python library for electronic structure pre/post-processing.

Version 6.2.0 created on Jun 10th, 2021

Please cite:
 Uthpala Herath, Pedram Tavadze, Xu He, Eric Bousquet, Sobhit Singh, Francisco Muñoz and Aldo Romero.,
 PyProcar: A Python library for electronic structure pre/post-processing.,
 Computer Physics Communications 251 (2020):107080.


Developers:
- Francisco Muñoz
- Aldo Romero
- Sobhit Singh
- Uthpala Herath
- Pedram Tavadze
- Eric Bousquet
- Xu He
- Reese Boucher
- Logan Lang
- Freddy Farah