On the evaluation of the solvent polarization apparent charges in the polarizable continuum model: A new formulation

A new formulation (CLS‐PCM) for the calculation of the apparent surface charges in the framework of the ab initio polarizable continuum model of the solvent (PCM) is introduced. Its performance is compared with that of the original iterative version (ITER‐PCM) of the method as well as with a matricial alternative formulation (matrix‐BEM‐PCM) of the same problem. Both CLS‐PCM and matrix‐BEM‐PCM have shown to be computationally more efficient than ITER‐PCM without presenting any problems associated with the convergence of the process. Although for small and medium‐size solutes the use of matrix‐BEM‐PCM is recommended, for neutral solutes of larger size the use of CLS2 becomes computationally more convenient. Finally, for very large‐size systems, compromise between matrix storage requirements, time of calculation, and exactness of the results may make preferable the use of the more approximate CLS1 formalism, possibly in conjunction with semiempirical or semiclassical descriptions of the solute.