Making use of Connolly's molecular surface program in the isodensity adapted polarizable continuum model

We present a general method to obtain well shaped cavities for treating sol vation within the polarizable continuum model (PCM). The cavities are built with Connolly's molecular surface program MSROLL, that allows easy evaluat ion of all the critical parameters involved in present day PCM technology. The procedure basically works in adapting the isodensity of the solutes at different threshold values. The important features to realize are, that on the one hand there is no uniform threshold value applicable for a reliable description of the solvation effect, and that on the other hand, there are two types of characteristic points to be found when plotting Delta G(el) ve rsus isodensity threshold value of the solute, which are, a minimum for neu tral and anionic molecules, or a shoulder for cationic molecules. Taking th e respective cavity dimensions at these characteristic points, the experime ntal values of Delta G(solv) are modeled within chemical accuracy and thus a true ab initio treatment of any arbitrary chemical system should be conce ivable within this so-called isodensity adapted polarizable continuum model (IDAPCM). (C) 2001 American Institute of Physics.