ANALYTICAL 1ST AND 2ND ENERGY DERIVATIVES IN THE POLARIZATION MODEL

The first and second derivatives of the induction energy with respect to displacements of the particle coordinates (forces and force constants) are calculated analytically in a system of interacting polarizable charges. While the forces can be evaluated on the basis of the permanent and polarization fields and their gradients, for the second derivative one needs explicitly the elements of the many-body polarization matrix. The self-consistent determination of the induced dipole moments may be of crucial importance. Consistent molecular dynamics (MD) calculations can be carried out either by using first-order induced dipoles or completely iterated ones. Premature stopping of the self-consistent iteration procedure may lead eventually to the non-conservation of the energy in longer molecular dynamics simulations. © 1990.