Questions tagged [gw-bse]

Questions about the GW approximation or the Bethe-Salpeter Equation (BSE).

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7 votes
1 answer
52 views

Is the HOMO energy obtained from GW calculation always a value relative to the vacuum energy (-Ip)?

Aim: I want to obtain a reasonably accurate ionization energy (or work function in other terms) for a 2-dimensional hBN monolayer. The exact material does not matter much respective to the question, ...
  • 231
3 votes
0 answers
132 views

Problem while performing the BSE GW calculations in VASP

I am trying to learn the BSE GW calculations in VASP. Using the procedure described on the VASP website. I am stuck at the last step 5 (BSE calculation). I didn't get any error in the 5th step but ...
8 votes
1 answer
302 views

VASP GW PAW Pseudopotentials

What is the difference between the GW and non-GW potentials in VASP. While it is clear that the GW potentials should be used with GW calculations, the documentation also states that these potentials ...
4 votes
1 answer
336 views

VASP GW+SOC band structure calculations

How may I carry out GW+SOC a band structure calculation using VASP? Could anyone familiar describe it step-by-step? I could not find any info regarding this on the VASP wiki.
  • 41
10 votes
1 answer
237 views

KS-DFT versus G0W0

The central equation that KS-DFT will solve is: $$\tag{1}\left[ -\dfrac{1}{2}\nabla^2+V_{ext}+V_{hartree}+V_{xc} \right]\psi_i(\vec{r})=E_i\psi_i(\vec{r})$$ Here $V_{xc}$ is approximated with LDA or ...
  • 14k
8 votes
2 answers
234 views

How to plot exciton wave function with phase information?

In GW-BSE calculations, people could analyze the exciton wave function $|S\rangle$ by plotting the BSE eigenvector $A_{cv\mathbf{k}}$ that satisfies $|S\rangle = \sum_{cv\mathbf{k}}A_{cv\mathbf{k}}|cv\...
8 votes
1 answer
115 views

How to evaluate the exciton velocity?

I have calculated the exciton wave functions using the GW-BSE method: $$\tag{1}|S\rangle = \sum_{cv\mathbf{k}} A_{cv\mathbf{k}} |cv\mathbf{k}\rangle$$ where $c$ for conduction and $v$ for valence ...
12 votes
1 answer
203 views

Recommended code to do XAS/XES/RIXS calculations with?

I am a grad student looking to simulate several XAS/XES and potentially RIXS spectra for some strongly correlated metal-oxides. The materials in question will likely require solving the Bethe-Salpeter ...
13 votes
0 answers
126 views

What are the recent developments of GW@BSE to simulate the excited properties of materials?

A twin question related to the TDDFT method is asked in another post. But any comparisons between both methods in recent developments are welcome. The time-dependent density functional theory (TDDFT) ...
  • 14k
19 votes
0 answers
148 views

What are the recent developments of TDDFT to simulate the excited properties of materials?

The time-dependent density functional theory (TDDFT) and the many-body perturbation method (GW@BSE) are considered as the two most popular and successful methods to describe the excited-stated ...
  • 14k
5 votes
1 answer
277 views

BSE and IQP oscillator strength from VASP

Recently I am trying to calculate the BSE and IQP transition dipole based on VASP lecture on BSE and BSE fatband. However, I have a few questions regarding the BSE and IQP oscillator strength. From ...
  • 675
10 votes
1 answer
165 views

Is there a software that has implemented forces of BSE calculations for solids?

I'd like to investigate the structural relaxations of the excited state for periodic systems. It seems BSE is a practical method that has already been implemented in many codes for static calculations....
10 votes
1 answer
174 views

What's the meaning of absorbance in the absorption spectrum calculated by the GW-BSE method?

Q1: As shown in the previous figure, what's the physical meaning of absorbance (y-axis) in the absorption spectrum calculated with the GW-BSE method? Q2: Here the absorbance for the absorption onset $...
  • 14k
21 votes
2 answers
371 views

What methods are available for excited state calculations in solids?

In the spirit of a succint answer (3 paragraphs maximum) to create a useful resource, what are the types of excited state calculation available for solids? Please add to the list: Quasiparticle ...
  • 10.4k
25 votes
3 answers
1k views

Given that Kohn-Sham DFT is strictly a ground-state method (at 0 K), how is it sufficient to describe materials in real-life applications?

Kohn-Sham DFT appears to be so popular even though it is strictly a ground-state method - all calculations are done at 0 K. How then, is it so popular when describing materials that have real-life ...
  • 2,336
15 votes
1 answer
268 views

Can GW-BSE quasiparticle calculations only be run on norm-conserving pseudopotentials (NCPPs)? If so, why not?

I've read in some texts that GW-BSE quasiparticle calculations have only been implemented on Norm-conserving Pseudopotentials (and not Ultra-soft or PAW PPs). Is there a conceptual reason for this? I ...
  • 2,336