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Bader charges for symmetric molecules

Posted: Mon Jan 13, 2014 3:44 pm
by andyrox
I have been using the Bader algorithm for the calculation of atomic charges on simple organic molecules through Gaussian09. While calculating the Bader charges, I came across a strange result.

For example, in the case of simple pyridine, the Bader charges on the two (chemically identical) C atoms in alfa-position with respect to N are markedly different (+1.27 and +1.16). This has no chemical meaning! The same also occurs on acridine: +1.43 and +1.47.

Does anyone know why it is like this? Do you know how to fix it? My Gaussian optimization was performed with DFT, with B3LYP functional and 6-31G** basis set. Dispersion effects (Grimme) have been introduced in the calculation via the IOpt(3/124=30) keyword.

Thank you in advance. Regards.

Andrea.