Total variance of the surface electrostatic potential

Definition:

- average value of the positive electrostatic potential in the molecule

- average value of the negative electrostatic potential in the molecule

V⁺(r_i) - positive electrostatic potential in the molecule

V ^-(r_i) - negative electrostatic potential in the molecule

m,n  - number of integration points

Reference:

1. P. Politzer, P. Lane, J. S. Murray, T. Brinck, J. Phys. Chem., 1992, 96, 7938.