Yambopy tutorial: band structures

The full tutorial, including the Quantum espresso and Yambo databases that we will read, can be downloaded and extracted from the yambo website:

$wget www.yambo-code.org/educational/tutorials/files/databases_qepy.tar
$tar -xvf databases_qepy.tar
$cd databases_qepy

Tutorial 1. BN (semiconductor). Band structure

The qepy classes are useful not only to execute Quantum Espresso but also to analyze the results. The full qepy library is imported by simply doing:

from qepy import *

Plot Band structure

The class PwXML reads the data file generated by Quantum Espresso and post-process the data. The class is initiated doing:

xml = PwXML(prefix='bn', path='bands')

The variable prefix corresponds to the same variable of the QE input. The folder location is indicated by variable path. Previously to plot the bands, we define the k-points path using the function Path:

npoints = 50
path_kpoints = Path([ [[0.0, 0.0, 0.0],'$\Gamma$'],
                      [[0.5, 0.0, 0.0],'M'],
                      [[1./3,1./3,0.0],'K'],
                      [[0.0, 0.0, 0.0],'$\Gamma$']], [int(npoints*2),int(npoints),int(sqrt(5)*npoints)])

It is worth to note that the path should coincide with the selected path for the QE calculations.

In order to plot we do:

xml.plot_eigen(path_kpoints)

This function will automaticall plot the bands as shown below.

Alternatively we can use the function plot_eigen_ax. This functions requires as input the figure object and with given axes, as in the next example.

Plot atomic orbital projected Band structure

Tutorial 2

Tutorial 3

Links

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