Accurately reproducing ab initio electrostatic potentials with multipoles and fragmentation

Abstract

In this work, we show that our energy based fragmentation method (Bettens, R. P. A.; Lee, A. M. J. Phys. Chem. A 2006, 110, 8777) accurately reproduces the electrostatic potential for a selection of peptides, both charged and uncharged, and other molecules of biological interest at the solvent accessible surface and beyond when compared with the full ab initio or density functional theory electrostatic potential. We also consider the ability of various point charge models to reproduce the full electrostatic potential and compare the results to our fragmentation electrostatic potentials with the latter being significantly superior. We demonstrate that our fragmentation approach can be readily applied to very large systems and provide the fragmentation electrostatic potential for the neuraminidase tetramer (ca. 24 000 atom system) at the MP2/6-31 l(+)G(2d,p) level. We also show that by using at least distributed monopoles, dipoles, and quadrupoles at atomic sites in the fragment molecules an essentially identical electrostatic potential to that given by the fragmentation electrostatic potential at and beyond the solvent accessible surface can be obtained. © 2009 American Chemical Society.