Applying a scissor operator

Concerns issues with computing quasiparticle corrections to the DFT eigenvalues - i.e., the self-energy within the GW approximation (-g n), or considering the Hartree-Fock exchange only (-x)

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rvatanme
Posts: 18
Joined: Thu Mar 26, 2015 5:33 am

Applying a scissor operator

Post by rvatanme » Wed Apr 15, 2015 6:59 am

Dear Users,

I would like to apply a scissor operator to correct the band gap of Silicon, but I don't know if yambo code has that ability or not. I'm just wondering if any one here knows how to use a scissor operator in yambo.

Best,
Reza
Reza Vatan Meidanshahi
Electrical Engineering Department
Arizona State University
USA

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Daniele Varsano
Posts: 4198
Joined: Tue Mar 17, 2009 2:23 pm
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Re: Applying a scissor operator

Post by Daniele Varsano » Wed Apr 15, 2015 12:20 pm

Dear Reza,

The variable to be set is:

Code: Select all

%KfnQP_E				
0.000000|1.000000|1.000000|		#	(EXTQP)(BSK)(BSS)	E parameters (c/v) eV|adim|adim
%
The first number is the scissor values, the other two are meant if you want also insert a stretching of the valence and conduction bands.
If you want just the scissor you leave them to 1. 00.
I assume that you want to apply it in the BSE framework, otherwise the variable name in RPA response is XfnQP_E, with the same usage.
Please note that the scissor it is used in the tutorials, I invite to have a look.
Best,
Daniele
Dr. Daniele Varsano
S3-CNR Institute of Nanoscience and MaX Center, Italy
MaX - Materials design at the Exascale
http://www.nano.cnr.it
http://www.max-centre.eu/

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