Journal of Physical Chemistry B, Vol.104, No.9, 2117-2122, 2000
Charge flow between ions and a dielectric continuum. 2. Variational method for distributing charge into the dielectric
The paper presents a variational method to distribute the charge transferred (CT) between an ion and a dielectric continuum onto a boundary element (BE) grid used to represent the dielectric continuum media. The CT charge is transferred into the dielectric using a methodology that combines a semiempirical effective Hamiltonian with a modified Poisson-Boltzmann equation, which includes CT in the form of a surface charge density positioned at the dielectric interface. The variational method eliminates the bias of our earlier method used to distribute CT charge into the dielectric, i.e., the need to specify the solute atoms used in constructing the BE grid. The surface "pattern" of the magnitudes of the CT charges placed onto the BE grid is obtained by minimizing an energy functional defined as the sum of the CT charge self-interaction energy and the energies due to CT charge interaction with the reaction field (RF) and solute partial atomic charges. The total amount of charge, distributed on the BE grid, is constrained to the amount of charge transferred from/to the solute HOMO/LUMO molecular orbital, by using the method of Lagrange multipliers.
Keywords:ELECTRONIC-STRUCTURE CALCULATIONS;MOLECULAR-ORBITALCALCULATIONS;BOUNDARY-ELEMENT METHOD;SOLVATION;MODELS