Dear Sir:
I have several questions
(1)After calculating GW correction I use -V qp to get the BSE parameters. I inserted the QP energy through KfnQPdb="E<./SAVE/db.QP" to the BS calculation. However, -V qp also listed many other parameters such as KfnQP_N, KfnQP_E,KfnQP_w, KfnQP_Z, XfnQPdb, XfnQP_N XfnQP_E, XfnQP_W XfnQP_Z etc. Can anyone briefly explain the physics meaning of those parameters? At moment I just use the default value. I am afraid to change any parameter.
(2) How can I insert GW energy to the RPA calculation. I used same method, -V qp. I cannot find parameter KfnQPdb to
add the QP energy. If I insert QP energy to the XfnQPdb="E<./SAVE/db.QP". The RPA spectrum did not change.
(3) We can find the indepencent particle approximation of the spectra from BSE and RPA output. I think two independent particle approximations should be same. However, they are different.
parameter of BSE
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- myrta gruning
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Re: parameter of BSE
Dear Chen
K and X at the beginning are saying to you to which quantity the corrections are applied, either the kernel (K) or the Chi (X)
KfnQP_E and XfnQP_E are the
QP corrections using a scissor operator and valence/conduction stretching.
in the format
scissor | cond. stretching | val. stretching
KfnQP_N and XfnQP_N
is the number of neighbors you want to use in case you calculated the QP corrections on a different k mesh
Sincerely I never used the other variables, that I think regard the QP correction to W and changing the renormalization factor, I think that they are used in some particular case and the default values (that means that those corrections are not used) are OK. Maybe others can detail more on the use of these variables
Are you getting any warning message in the log or report?
In general if you encounter any problem you should post inputs and outputs of the calculation in question otherwise it is very difficult for us to understand what is going on
Finally, please fill-in your signature, so that it will appear automatically in each post.
I hope this helps,
Myrta
First note that XfnQPdb, XfnQP_N XfnQP_E, XfnQP_W XfnQP_Z are the analogue of KfnQPdb, KfnQP_N KfnQP_E, KfnQP_W KfnQP_ZKfnQP_N, KfnQP_E,KfnQP_w, KfnQP_Z, XfnQPdb, XfnQP_N XfnQP_E, XfnQP_W XfnQP_Z etc. Can anyone briefly explain the physics meaning of those parameters? At moment I just use the default value. I am afraid to change any parameter.
K and X at the beginning are saying to you to which quantity the corrections are applied, either the kernel (K) or the Chi (X)
KfnQP_E and XfnQP_E are the
QP corrections using a scissor operator and valence/conduction stretching.
in the format
scissor | cond. stretching | val. stretching
KfnQP_N and XfnQP_N
is the number of neighbors you want to use in case you calculated the QP corrections on a different k mesh
Sincerely I never used the other variables, that I think regard the QP correction to W and changing the renormalization factor, I think that they are used in some particular case and the default values (that means that those corrections are not used) are OK. Maybe others can detail more on the use of these variables
As I said above KfnQPdb regard the kernel, that is why it is not in RPA where you have instead the same quantities for X (Chi)2) How can I insert GW energy to the RPA calculation. I used same method, -V qp. I cannot find parameter KfnQPdb to
add the QP energy. If I insert QP energy to the XfnQPdb="E<./SAVE/db.QP". The RPA spectrum did not change.
Are you getting any warning message in the log or report?
Are you sure you are doing the same calculations, using the same parameters?(3) We can find the indepencent particle approximation of the spectra from BSE and RPA output. I think two independent particle approximations should be same. However, they are different.
In general if you encounter any problem you should post inputs and outputs of the calculation in question otherwise it is very difficult for us to understand what is going on
Finally, please fill-in your signature, so that it will appear automatically in each post.
I hope this helps,
Myrta
Dr Myrta Grüning
School of Mathematics and Physics
Queen's University Belfast - Northern Ireland
http://www.researcherid.com/rid/B-1515-2009
School of Mathematics and Physics
Queen's University Belfast - Northern Ireland
http://www.researcherid.com/rid/B-1515-2009
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- Posts: 41
- Joined: Thu Apr 01, 2010 2:23 pm
Re: parameter of BSE
Dr. Myrta:
Thank you.
Zhifan chen
Dept of Physics
Clark Atlanta University
USA
Thank you.
Zhifan chen
Dept of Physics
Clark Atlanta University
USA