Analysis of BSE excitations

[martijn]

Hi,

I have some questions regarding analysis of the excitations obtained using GW/BSE:

1) Are the oscillator strengths, transition dipole moments and orbital contributions calculated using GW/BSE meaningful? The manual I think only mentions excitation energies but the code also calculates this other properties.

2) What is possible in terms of density analysis? In JCC 2017, 38, 383 transition densities and natural transition orbitals are mentioned. I have managed to calculate the former, though I only seem to be able to plot one component using Jmol or VMD, and I think I have extracted the GW/BSE NTOs (thanks to @finrod's post in on the visualization page).

Thanks,

Martijn

[uwe]

Hi,

NTOs can be visualized using TmoleX. If you import a job into the graphical user interface (File menu -> "Open Job/Control File"), and if the plt files are all in the directory, TmoleX will list them in the Results -> "Orbital/Density Plot" window.

Regards,

Uwe

[chris.hol]

Hi Martijn,

1) Yes, the GW/BSE oscillator strength and other properties are meaningful. Use them just like the TD-DFT ones. Actually, the oscillator strengths seem to be rather good (see J. Chem. Theory Comput. 2016, 12, 8, 3969–3981; also we found the lifetimes in 2c GW/BSE calculations to be often better than their TD-DFT counterparts). However, GW/BSE oscillator strengthts do not obey the sum rules as TD-DFT (so velocity/length representations will not coincide for a complete basis set), if one is very strict about these things.

2) As Uwe said, you can visualize NTOs just like TD-DFT using the proper program, there select the mos / dftnto menu. the dftnto menu will actually recognize the $bse flag and report something like "found $bse flag, assuming BSE response calculation". The transition density of JCC 2017, 38, 383 can be obtained from the "panama" script, which should also be compatible with GW/BSE (we recommend the use of NTOs though)

All the best
Christof

[martijn]

Thanks Uwe & Christof. That's very useful.