ESP (Electrostatic Potential in NWChem)

Just Got Here

6:33:02 AM PDT - Tue, Jul 18th 2017

I am concerned about the units of the ESP in NWChem. Consider the data on HF in the output file:

1 a.u. = 9.07618 esu/cm ( or statvolts )

Point X Y Z Total Potential(a.u.) Diamagnetic shielding(a.u.)

   1 F    0.00000   0.00000  -0.08806     -26.551580            27.123542

   2 H    0.00000   0.00000   1.66031      -0.905417             6.053075

Now consider the same data from Gamess on the same molecule:

electric potential 1 a.u. = 9.076814E-02 esu/cm

                                 Total Potential (a.u.)             Diamagnetic shielding (a.u.)

        F                                -26.554587                        27.126252

        H                                -0.902754                          6.047740

Is it possible that NWChem has an error in the conversion factor from a.u. to esu/cm?

Just Got Here

2:17:39 PM PDT - Tue, Jul 18th 2017
Proof of an error using an H atom
The potential energy of H in the ground state is exactly 27.2116 Volts The calculated potential energy = constant * 299.7925 * the calculated value in A.U. The value, 299.7925 is the conversion from esu/cm to volts where esu / cm are the units of the electrostatic potential energy in NWChem or Gamess. constant(NWChem) = 9.07618, constant(Gamess)=0.09076814 V(Gamess) = 0.09076814 * 299.7925 * (-0.990160) = -26.943845 Volts V(NWChem) = 9.07618 * 299.7925 * (-0.990745) = -2695.788108 Volts V(Exact) = 27.2116 Volts The results suggest that NWChem may have an error in the conversion constant.

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