From: Emma Wu (
Date: Sat Jan 30 2021 - 20:31:30 CST

I am trying to parameterize a molecule that has a lone pair with fftk. I am
in the process of optimizing its charges using the RESP method. However,
this is the error message I run into:
"Element name of the following atom was not recognized. Please check atom
names in your input PDB/PSF files: X"

When I go into the pdb, I see that there is no atom type assigned for the
lone pair. I got the pdb/psf using a str file from cgenff and fftk.

Any help/advice is appreciated! Thank you!