Use of molecular symmetry in the computation of solvation energies and their analytical derivatives by the polarizable continuum model

We describe an effective way of taking into account molecular symmetry in the computation of solvation energies and their analytical derivatives by the polarizable continuum model (PCM). Implementation of this algorithm in the Gaussian series of programs leads to remarkable savings of computer time without introducing any significant numerical noise. Coupling of this approach with other algorithmic improvements of the PCM implementation in Gaussian (e.g., effective iterative procedures and analytical second derivatives) further reduces the gap between the computations feasible in vacuo and in condensed phases.