Geometry optimization of molecular structures in solution by the polarizable continuum model

A new implementation of analytical gradients for the polarizable continuum model is presented, which allows Hartree-Fock and density functional calculations taking into account both electrostatic and nonelectrostatic contributions to energies and gradients for closed and open shell systems. Simplified procedures neglecting the derivatives of the cavity surface and/or using single spheres for XHn groups have also been implemented and tested. The solvent-induced geometry relaxation has been studied for a number of representative systems in order to test the efficiency of the procedure and to investigate the role of different contributions. (C) 1998 John Wiley & Sons, Inc.