[Pw_forum] Bands.x not ordering bands correctly

[Henry J Seeley]

Hello everyone,

I'm using bands.x to assign eigenvalues to specific bands of PbS. I have 
fairly large supercells (20-30 atoms), so my bands are dense with lots 
of crossings. When I run bands.x it incorrectly assigns bands resulting 
in erratic band diagrams (e.g., bands suddenly jump across the bandgap 
to connect conduction and valence eigenvalues). What are the potential 
causes of this error?

Perhaps I am not sampling my k-points densely enough; I have 
approximately 10-15 points per sampling line. I plan on increasing this 
density to 50 kpts per line, and will report back if this solves the 
problem. I am somewhat in a rush to get these results though, so if 
anyone has some insight it would be much appreciated.

Also, assuming there is a solution to this problem, is band.x capable of 
sorting a 2D grid of kpoints into bands? I am interesting in generating 
contour maps.

Thank you,
Hank Seeley
Chemistry PhD student
University of Oregon