Multiwfn forum / Suggested Additions to Electron Excitation Analysis

Re: Suggested Additions to Electron Excitation Analysis

dummy@example.com (sobereva) — Sat, 27 May 2023 01:55:06 +0000

Dear Chase,

Yes, hole-electron analysis currently doesn't support EOM-CCSD.

Best,

Tian

Re: Suggested Additions to Electron Excitation Analysis

dummy@example.com (chrotteg) — Fri, 26 May 2023 00:40:38 +0000

Dear Prof Tian,

Thank you so much for the very useful information as I am unfamiliar with how a lot of these values are calculated currently. From what I gathered from the manual, I am assuming doing hole-electron analysis is currently not avaiable for CCSD in Multifwn? Thank you for so much of your help again. I greatly appreciate it!

Best,
Chase

Re: Suggested Additions to Electron Excitation Analysis

dummy@example.com (sobereva) — Fri, 26 May 2023 00:08:01 +0000

Dear Chase,

This analysis has some correlations with hole-electron analysis. The charge density difference (△ρ) used in this analysis is formally identical to ρ(electron) - ρ(hole). The advantage of hole-electron analysis is that the cancellation between hole and electron is avoided, and thus the integral of hole or electron is exactly 1.0, which is fully physically meaningful (at least for single-electron excited state). In contrast, due to cancellation effect, the integral of absolute value of positive or negative of △ρ must more or less deviate from 1.0. Therefore, hole-electron analysis provides somewhat richer information about nature of the excitation.

Best,

Tian

Re: Suggested Additions to Electron Excitation Analysis

dummy@example.com (chrotteg) — Thu, 25 May 2023 22:38:44 +0000

Dear Prof Tian,

Thank you so much for your help! I will definitely look into your suggestions. With your first suggestion, I looked into the electron density difference and saw the output in the manual. The data is output as positive and negative components which makes sense. I was curious if this correlates to electron and hole analysis? If this does not, is it possible to do electron-hole analysis with EOM-CCSD? Thank you so much for your help again.

Best,
Chase

Re: Suggested Additions to Electron Excitation Analysis

dummy@example.com (sobereva) — Thu, 25 May 2023 22:05:06 +0000

1 Multiwfn supports many different ways to analyze electronic excitation, EOM-CCSD is supported by some of them. For example, as illustrated in Section 4.18.3 of manual, if you want to perform electron excitation based on electron density difference, you just need to provide wavefunction file for ground state and excited state. If the ground state wavefunction file contains HF orbitals (i.e. reference wavefunction), and the excited state wavefunction contains natural orbitals at EOM-CCSD level (for example, can be generated by EOM-CCSD calculation of Gaussian with "density" and "out=wfn" keywords), then the analysis result will correspond to EOM-CCSD level.

2 You should export cube file of hole and electron respectively. Then you can use VMD to simultaneously plot isosurfaces of the two cube files. Please check Section 4.A.14 of Multiwfn manual, I've provided a VMD script to very easily realize this.

Suggested Additions to Electron Excitation Analysis

dummy@example.com (chrotteg) — Thu, 25 May 2023 01:02:49 +0000

Hi! I have just recently started using multiwfn and it has been extremely useful with my work in anaylzing excited states. This correlates to me spending all my time in the electron excitation analysis section, however, I have run into some issues that I was curious could be solved. My first issue is I wanted to upgrade to EOM-CCSD calculations but I saw that multiwfn does not support CCSD for the excitation analysis section. I was curious if this was possible to implement in the future? I understand that is probably an extremely daunting task so I understand am shooting for the starts requesting it. The other issue I ran into was when doing the electron-hole analysis, my work has found use in plotting the isosurface of the hole and electron distribution simultaneously (Option 3 after creating the grid). I plan to make high-resolution figures for this option, however, it is the only option that doesn't have a secondary option to export a cube file. If I could get help in how to export a cube file for this or have another way to make nice images that would be amazing. Thank you for time and help!