I am trying to understand the implementation of OEP and HF in elk. In Betzinger et al PRB 2011 on OEP it seems the equations are all diagonal in k (unless I missed something), but in the code it seems there is a sum over k and k' (gridk and gridq . (Is this right). Where does the sum over k' come from? Is there a better reference? (It would be very useful to have a list of references for different techniques in ELK. Is there? )
Also it is not clear to me the inner loop and why so many iterations (like 300) are needed. I am getting like 1-2 scf per day for an 8 atom cell with OEP .
Now in HF there is a sum over k and k' and that seems to fit with the implementation. But what is the best reference for how it is done in elk? Finally, will it be possible to do screened hybrid like HSE as in Tran and Blaha? Thank you!
Sincerely,
Ron Cohen
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I am trying to understand the implementation of OEP and HF in elk. In Betzinger et al PRB 2011 on OEP it seems the equations are all diagonal in k (unless I missed something), but in the code it seems there is a sum over k and k' (gridk and gridq . (Is this right). Where does the sum over k' come from? Is there a better reference? (It would be very useful to have a list of references for different techniques in ELK. Is there? )
Also it is not clear to me the inner loop and why so many iterations (like 300) are needed. I am getting like 1-2 scf per day for an 8 atom cell with OEP .
Now in HF there is a sum over k and k' and that seems to fit with the implementation. But what is the best reference for how it is done in elk? Finally, will it be possible to do screened hybrid like HSE as in Tran and Blaha? Thank you!
Sincerely,
Ron Cohen