WATER WATER INTERACTION POTENTIAL - AN APPROXIMATION OF THE ELECTRON CORRELATION CONTRIBUTION BY A FUNCTIONAL OF THE SCF DENSITY-MATRIX

The approximate expression for the correlation energy suggested by Colle and Salvetti (1975), but modified with a different set of parameters obtained by a more accurate description of the Coulomb hole, has been applied to approximate the electron correlation in the water two-body interaction potential. The results obtained are in good agreement with previous configuration interaction and perturbative computations, indicating that the approach can be applied successfully to calculate the correlation contribution in interaction potentials between large molecules with a reasonable computational effort. With the new two-body potential, a Monte Carlo simulation of liquid water has been carried out and a comparison of computed and experimental results is presented for the internal energy, the oxygen-oxygen radial distribution function, and the neutron scattering structure function.