BSEBands, HARRLvcs, EXXRLvcs, and CORRLvcs for IPA and BSE

[sunxl]

Dear all,

When performing IPA-SHG calculations, I noticed that there are three parameters: BSEBands, HARRLvcs, and EXXRLvcs. However, for BSE-SHG calculations, there are four parameters: .BSEBands, HARRLvcs, EXXRLvcs, and CORRLvcs.

1、If I have already performed convergence tests for the three parameters in IPA calculations (e.g., BSEBands = 3-6 and HARRLvcs = EXXRLvcs = 2Ry), can I directly set BSEBands = 3-6 and HARRLvcs = EXXRLvcs = CORRLvcs = 2Ry for BSE-SHG calculations?

2、For HARRLvcs, EXXRLvcs, and CORRLvcs, is it necessary to keep these parameters equal to each other, or can they be set independently?

Thank you in advance for your help!

Best,
sunxl

[claudio]

Dear sunxl

for IPA you have just to converge the number of bands and that's all.

For HARTREE you need to converge bands and HARRLvcs

for TD-DFT bands, HARRLvcs and EXXRLvcs

than for BSE with COLLISIONS all together.
But my advise is to put them all equal to avoid confusion, in principle you can set them different but I do not have
a particular reason to do it.
Notice that these parameters has to be the same using the collision calculations

best
Claudio