Results for Potential-Derived Net Atomic Charges

To measure the agreement of the QM potential with the model potential the root-mean-square fit may be used  

Both rms and rrms are sensitive to the choice of grid point locations where the QM potential is evaluated. Typical values of rms and rrms are 1 to 3 kJ/mol and 3 to 9% with 6-3IG wavefunctions. The fit generally worsens as grid points are placed closer to the molecule. In certain cases (e.g., strong lone pair effect) worse fits may be obtained with net atomic charge models. Models utilizing additional nonatomic sites, site dipoles, and/or quadrupoles usually give a much better fit. 

Here values of PD net atomic charges are summarized from the literature. Unless otherwise stated, 6-3IG wavefunctions were used to calculate the 

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