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Numerical solution of boundary-integral equations for molecular electrostatics.

Journal Article · · J. Chem. Phys.
DOI:https://doi.org/10.1063/1.3080769· OSTI ID:951574
Numerous molecular processes, such as ion permeation through channel proteins, are governed by relatively small changes in energetics. As a result, theoretical investigations of these processes require accurate numerical methods. In the present paper, we evaluate the accuracy of two approaches to simulating boundary-integral equations for continuum models of the electrostatics of solvation. The analysis emphasizes boundary-element method simulations of the integral-equation formulation known as the apparent-surface-charge (ASC) method or polarizable-continuum model (PCM). In many numerical implementations of the ASC/PCM model, one forces the integral equation to be satisfied exactly at a set of discrete points on the boundary. We demonstrate in this paper that this approach to discretization, known as point collocation, is significantly less accurate than an alternative approach known as qualocation. Furthermore, the qualocation method offers this improvement in accuracy without increasing simulation time. Numerical examples demonstrate that electrostatic part of the solvation free energy, when calculated using the collocation and qualocation methods, can differ significantly; for a polypeptide, the answers can differ by as much as 10 kcal/mol (approximately 4% of the total electrostatic contribution to solvation). The applicability of the qualocation discretization to other integral-equation formulations is also discussed, and two equivalences between integral-equation methods are derived.
Research Organization:
Argonne National Laboratory (ANL)
Sponsoring Organization:
SC
DOE Contract Number:
AC02-06CH11357
OSTI ID:
951574
Report Number(s):
ANL/MCS/JA-62198
Journal Information:
J. Chem. Phys., Journal Name: J. Chem. Phys. Journal Issue: Mar. 7, 2009 Vol. 130; ISSN JCPSA6; ISSN 0021-9606
Country of Publication:
United States
Language:
ENGLISH

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