Multiwfn forum

You can use the following:

$write
   density=true
$cube
    step=0.05

It took me a while to find this as well, but https://github.com/grimme-lab/xtb/blob/ … rol.7.adoc provides a good reference.

The wavefunction is loaded correctly, according to the checks in Appendix 5.

I noticed that I cannot find all (3, -3) critical points in water following an xTB calculation (starting the search at the atom positions). Looking at the density isosurfaces generated from the cubes files from xTB and Multiwfn respectively (both with isovalue 0.082 in VMD), it seems that the Multiwfn-generated cube file does indeed not have a maximum at the hydrogen nuclei which seems counterintuitive to me (while the xTB-generated one shows maxima). Could search for those (3, -3) critical points with other search parameters be more successful?

Thank you very much for the detailed answer, and apologies for my late reply. I have now tried the suggested steps (using latest version of Multiwfn, 3.8). Interestingly, the difference between xTB and Multiwfn persists also when I set isupplyEDF=0 in settings.ini ("Loading electron density functions..." isn't shown anymore during startup of Multiwfn).

Also, I get the same cube files from Multiwfn independent of whether I set isupplyEDF to 0 or 2 (though the message during startup changes, so the settings.ini file is read correctly). In each case it says that "This file is found to be generated by xtb! Special treatment is applied...", though only if isupplyEDF = 2 it also says "Loading electron density functions (EDF) information from built-in EDF library".

Perhaps the discrepancy is indeed on the xTB side for generating the cube files.

Thanks for your help! Just wanted to check before writing this up