Momentum density of silicon valence band using bandstructure

[Samisdabes]

TL;DR Summary

I am attempting to use python to calculate the gradient of the bandstructure for the 3 bands in the valence band for a bandstructure, at a discrete set of points and then plot them in a histogram to get the electron momentum density curve. However I have problems.

I have included the resulting histogram that emerges when I do this procedure and it does not look as expected. I am using CASTEP and have read the .bands file as a txt file into python where i have extracted the relevant data.

 

[Dr Transport]

Why do you need the gradients? Your plot doesn't really make any sense to me.