problems with bse

[samaneh]

Dear developers
I have some questions about bse calculations
1- Is it necessary to do first yambo -b and then yambo -o b -k sex -y h
since I do not use the command yambo -b and only run the command
yambo -o b -k sex -y h
and also for Qp calculation I do not run the command yambo -b -k hartree
I just run the yambo -g n -p p???
2- I do not know the meaning of the wehcpl (e-h interaction included in coupling!) in the input file of bse calculation?
S. Ataei, University of Tehran, Iran

[Daniele Varsano]

Dear Samaneh,
1) yambo -b prepare the input for the static screening. You need it in order to build the sex kernel. It should be done by default if not specified, check you have
the

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em1s

keyword in your input, otherwise you can add the -b in the command line:

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 yambo -b -o b -k sex -y h

When building up the screening "Hartree" is the default. (Check Chimod).


2) GW self energy has dynamical screening, for this reason you do the plasmon pole (-p p) and not the static screening (-b).

3) If you want to go beyond the Tamm-Dancoff approximation, ie include the coupling:

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BSEmod="coupling"

you can include the exchange only in the coupling part of the matrix or also the direct term. In order to include the latter you need to uncomment the WehCpl variable.

Best,
Daniele