WebMO Support Forum

I am still having trouble with MO calculations on carbocations (see also post on MO visualizations). But first consider t-butyl anion: Build C3C and set central atom charge to -1. Cleanup Mechanics - gives pyramidal central carbon. Thus WebMO recognizes the correct hybridization of that atom and the...

Here is a strange result using the WebMO app on an ipad v10: Lookup, Import, "crystal violet" gives the Ar3C+ Cl- ion pair. Then calculate orbitals shows the LUMO that looks correct for Ar3C+ ion itself, i.e. with large lobe on the central C. Deleting the Cl- ion, then repeating calculate ...

To be clear, since v 17 or so WebMO has included an interactive Geometry Sequence display that functions as described above. For Gaussian, MOPAC and xTB, the progress of optimizations is updated in real time. For a large systems or long optimization times this is extremely useful. But in the case of...

For WebMO 23, edit the parse-mopac.cgi file as follows:
in line 50: change "MOPAC v22" to "MOPAC v23'
in line 51: change "2022" to "2023"

On my machine, using several different browsers, and on your WebMO demo, the Lookup, By Name menu shows databases grayed out. Search for "aspirin" fails. In fact several of these databases are online and working normally. What am I doing wrong?

Thanks, JR. I see that option on the Advanced Tab of XTB in v. 24 of WebMO!

In parse_orca.cgi (WebMO 23) changing "LOEWDIN" to "MULLIKEN" in line 278 gives the Mulliken charges in the Partial Charge table with the correct atom numbers. However, an extra line labeled "1" is seen at the bottom of the table, and the link to the ViewPartialCharge_m...

How might one edit the parse_orca.cgi file to recover Mulliken charges rather than Loewdin charges?

Yes, this can be done by adding a few lines to the run_xtb.cgi file. Contact jwkeller@alaska.edu if you want the details.

In the meantime, can we just force xtb to do "--opt vtight" on all optimizations, rather than "--opt" ?