Calculation of electrostatic and polarization energies from electron densities.

We investigate procedures for calculating the electrostatic and polarization energies, Ees and Epol, associated with noncovalent interactions. The starting points are the electron densities of the isolated components and the complex; these could be obtained either computationally or experimentally. A slightly modified version of a scheme proposed by Gavezzotti is used to carry out numerical integrations over these electron densities. Our approach to estimating Epol is based upon partitioning the charge distributions of the components into overlapping and nonoverlapping regions. The effects of varying the integration parameters, computational techniques and basis sets are examined in detail for several noncovalently bound molecular dimers. Our results are in good agreement with the values of Ees and Epol produced by other methods, which require analytical integrations over interaction Hamiltonian matrix elements. Copyright 2004 American Institute of Physics