Do not all load wave functions (dipoles) from DB when initializing the class

[cskern]

When initializing the class YamboWFDB, the full wave functions are loaded into memory by default. This is only feasible for very small systems and should be avoided.

Ideally, the wave functions could be loaded with a separate function and possibly for each (spin-channel,) band and k-point. Apparently this affects also the the database for the dipoles and maybe others as well?

[muralidhar-nalabothula]

Hi @cskern,

If you are using the master branch, you can indeed select the bands you want.
abc = wfdb.YamboWFDB(path='.', bands_range = [5,10]) (python indexing for bands, left band included and right excluded).

The choice to select particular k and spin was not-included as very often we need to load the full k-points. I doubt this will be added as I implemented it in the first place and later removed as it was making the class more complicated. But neverthless, in case you really want load only a certain k point and spin, you can directly use the code block as given here https://github.com/yambo-code/yambopy/blob/master/yambopy/dbs/wfdb.py#L172

Best regards,
Murali