Multiwfn forum

Hello,

I wish to use Multiwfn to compute the magnetic and electric transition dipole moments (MTDM and ETDM) from my Gaussian output, using option 18 → 5.

However, a question remains regarding units: Multiwfn labels both quantities as "atomic units", but I am unsure whether the MTDM is given in Bohr magnetons (μ_B) or in e·a₀. These are not the same unit — they differ by a factor of α/2, where α is the fine structure constant.
My goal is to compute the luminescence dissymmetry factor using:

g_lum = 4·|μ|·|m|·cos(θ) / (|μ|² + |m|²)

For this formula to be dimensionally consistent, both |μ| and |m| must be expressed in the same units. So the question is: should I convert the MTDM from μ_B to e·a₀ by multiplying by α/2?

I found one reference explicitly documenting Gaussian's convention (Garner & Corminboeuf, PCCP 2023, ESI), which states that magnetic transition dipole moments from Gaussian are given in Bohr magnetons — implying that the conversion is necessary. However, I have not been able to confirm whether Multiwfn preserves this convention or internally converts to e·a₀ before printing.

Thank you for your help.