Variable van der Waals Radii Derived From a Hybrid Gaussian Charge Distribution Model for Continuum-Solvent Electrostatic Calculations

Renlong Ye 1 , Xuemei Nie 1 , Chung F. Wong 2 , Xuedong Gong 1 , Yan A. Wang 3 , Thomas Heine 4  and Baojing Zhou 1
  • 1 Computational Institute for Molecules and Materials, School of Chemical Engineering, Nanjing University of Science and Technology, Xiaolingwei 200, 210094 Nanjing, China
  • 2 Department of Chemistry and Biochemistry and Center for Nanoscience, University of Missouri-Saint Louis, One University Boulevard, 63121 Saint Louis, USA
  • 3 Department of Chemistry, University of British Columbia, V6T 1Z1 Vancouver, Canada
  • 4 School of Engineering and Science, Jacobs University Bremen Campus Bremen, Ring 1, 28759 Bremen, Germany

Abstract

We introduce a hybrid Gaussian charge distribution model (HGM) that partitions the molecular electron density into overlapping spherical atomic domains. The semi-empirical HGM consists of atom-centered spherical Gaussian functions and discrete point charges, which are optimized to reproduce the electrostatic potential on the molecular surface as well as the number of electrons in atom-centered and certain off-atom-centered spherical regions as closely as possible. In contrast, our previous Gaussian charge distribution model [J. Chem. Phys. 129, 014509 (2008)] contained only spherical Gaussian functions and was not required to reproduce the number of electrons in off-atom-centered regions. Variable van der Waals (vdW) radii fluctuating around the Bondi radii are derived from the HGM based on the isodensity contour concept and further employed to define the molecular cavity in our quantum mechanical/Poisson–Boltzmann/surface area model as well as the polarizable continuum model. The variable vdW radii produce more accurate solvation free energies for 31 neutral molecules than the Bondi radii for both continuum solvent models (CSM) consistently. Moreover, for H atoms, the linear dependence of the atomic radii on the atomic partial charges is identified.

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Founded in 1887, the Zeitschrift für Physikalische Chemie covers the main developments in physical chemistry, placing with an emphasis on experimental research. It represents a combination ofdiscusses reaction kinetics and spectroscopy, surface research and electrochemistry, thermodynamics and the structure analysis of matter in its various conditions, among other topics.

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