BSE calculation
Moderators: Global Moderator, Moderator
-
flybird0303
- Newbie
- Posts: 2
- Joined: Sun Nov 03, 2013 4:00 pm
BSE calculation
[quote="'smallblacktext'>[ Edited Mon Nov 04 2013, 04:48AM "]</span>
Last edited by flybird0303 on Mon Nov 04, 2013 4:47 am, edited 1 time in total.
-
giacomo giorgi
- Full Member
- Posts: 122
- Joined: Tue Mar 10, 2009 2:04 am
BSE calculation
Isabel. Please excuse me for the terribly late reply. I just noticed your post right now.
Flybird0303. In DFT you use an exchange-correlation potential (Vxc), in GW you use a screened Coulomb potential (W). This makes the difference
Flybird0303. In DFT you use an exchange-correlation potential (Vxc), in GW you use a screened Coulomb potential (W). This makes the difference
Last edited by giacomo giorgi on Tue Nov 05, 2013 4:03 am, edited 1 time in total.
-
gbal
- Newbie
- Posts: 17
- Joined: Mon Oct 12, 2009 2:25 pm
- License Nr.: 5-82
- Location: Stockholm, Sweden
BSE calculation
Hej people,
Thanks to this tread i was able to finish some BSE calculations. However, i went to get bibliografy for it and the methods seems to vary a bit (at least at first look). Do you know any references for the implementation in vasp? In the code they talk about Tamm-Dancoff approximation, but this ain't much help, as seems all the people use it.
Thanks a lot anyway!
Thanks to this tread i was able to finish some BSE calculations. However, i went to get bibliografy for it and the methods seems to vary a bit (at least at first look). Do you know any references for the implementation in vasp? In the code they talk about Tamm-Dancoff approximation, but this ain't much help, as seems all the people use it.
Thanks a lot anyway!
Last edited by gbal on Thu Nov 07, 2013 3:20 pm, edited 1 time in total.
-
yunhailiseu
- Newbie
- Posts: 6
- Joined: Mon Mar 11, 2013 1:16 pm
- License Nr.: 785
BSE calculation
[quote="yunhailiseu"]There are two basic electronic excitations : charged excitation in which one electron is removed from or added to the system, and neutral excitation in which the number of electrons remain unchanged. GW method is designed to deal with the former, while BSE for the later.
...........................
[/quote]
Firstly, generate a large number of Kohn-Sham orbitals on a regular k-grid.
Secondly, do GW calculation using wavefunctions generated in DFT calculation to obtain quasi-particle energies.
Finally do BSE calculation.
GW gap describes the energy required to remove an electron from a N-electron system, while DFT gap is more like the energy required to excite an electron. It is obvious that removing an electron takes more energy.
<span class='smallblacktext'>[ Edited Wed Nov 27 2013, 02:34PM ]</span>
...........................
[/quote]
Firstly, generate a large number of Kohn-Sham orbitals on a regular k-grid.
Secondly, do GW calculation using wavefunctions generated in DFT calculation to obtain quasi-particle energies.
Finally do BSE calculation.
GW gap describes the energy required to remove an electron from a N-electron system, while DFT gap is more like the energy required to excite an electron. It is obvious that removing an electron takes more energy.
<span class='smallblacktext'>[ Edited Wed Nov 27 2013, 02:34PM ]</span>
Last edited by yunhailiseu on Wed Nov 27, 2013 2:31 pm, edited 1 time in total.