Gaussian is not absolutely needed. However, currently Multiwfn can only automatically invoke Gaussian to compute atomic wavefunction files and properly sphericalize them, see Section 3.7.2 of Multiwfn manual for details. Perhaps ORCA will be supported in the future versions.

If you are using other quantum chemistry programs, you need to manually generate the sphericalized atomic wavefunction files one by one, and use custom operation feature of Multiwfn to plot electron deformation density.

Best,

Tian

I'm trying to calculate the electron deformation density.

From what I saw in the document (4.4.7), Multiwfn needs to invoke Gassuan to perform the analysis (for calculating the single-electron density, I presume). I am wondering if it is possible to use other quantum chemistry software, e.g. Gamess-US, to do the same calculation?

Thanks in advance.