Multiwfn forum

fyzan

Member

Registered: 2020-01-25

Posts: 21

Different oscillator strength of Multiwfn two-level & gaussian logfile

Hi, the oscillator strength of an excited state output by two-level model in Multiwfn is different from the td-dft log file of gaussian. which one to use?

sobereva

Tian Lu (Multiwfn developer)

From: Beijing

Registered: 2017-09-11

Posts: 1,773

Website

Re: Different oscillator strength of Multiwfn two-level & gaussian logfile

Note that the oscillator strength in common sense is calculated based on total transition dipole moment, while the current oscillator strength printed by Multiwfn is calculated based on the component of transition dipole moment you selected, therefore the values are different (i.e. X component). I suggest you read corresponding part of Multiwfn manual (i.e. Section 3.200.8.2) first to gain relevant knowledge, so that you can select meaningful component in your analysis.

fyzan

Member

Registered: 2020-01-25

Posts: 21

Re: Different oscillator strength of Multiwfn two-level & gaussian logfile

From the manual I get that we select dominant component i.e Z and we have to report only Z component of transition dipole moment (Oscillator strength) and variation of dipole moment as BetaZZZ based only on Z component. we don't need to report total oscillator strength/tot transition dipole moment for the sake of discussion in two level model?did I get this correct or I'm making any mistake?

sobereva

Tian Lu (Multiwfn developer)

From: Beijing

Registered: 2017-09-11

Posts: 1,773

Website

Re: Different oscillator strength of Multiwfn two-level & gaussian logfile

Strictly speaking, in this context, you should only report Z component of transition dipole moment (or the corresponding oscillator strength). However, many papers report oscillator strength calculated based on total transition dipole moment, this is also not unacceptable...

fyzan

Member

Registered: 2020-01-25

Posts: 21

Re: Different oscillator strength of Multiwfn two-level & gaussian logfile

Thank you sir for your good advice.