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Method for Slater-Type Density Fitting for Intermolecular Electrostatic Interactions with Charge Overlap. I. the Model

Öhrn, Anders LU ; Hermida-Ramon, Jose M. LU and Karlström, Gunnar LU (2016) In Journal of Chemical Theory and Computation 12(5). p.2298-2311
Abstract

The effects of charge overlap, or charge penetration, are neglected in most force fields and interaction terms in QM/MM methods. The effects are however significant at intermolecular distances near the van der Waals minimum. In the present study, we propose a method to evaluate the intermolecular Coloumb interaction using Slater-type functions, thus explicitly modeling the charge overlap. The computational cost of the method is low, which allows it to be used in large systems with most force fields as well as in QM/MM schemes. The charge distribution is modeled as a distributed multipole expansion up to quadrupole and Slater-type functions of angular momentum up to L = 1. The exponents of the Slater-type functions are obtained using a... (More)

The effects of charge overlap, or charge penetration, are neglected in most force fields and interaction terms in QM/MM methods. The effects are however significant at intermolecular distances near the van der Waals minimum. In the present study, we propose a method to evaluate the intermolecular Coloumb interaction using Slater-type functions, thus explicitly modeling the charge overlap. The computational cost of the method is low, which allows it to be used in large systems with most force fields as well as in QM/MM schemes. The charge distribution is modeled as a distributed multipole expansion up to quadrupole and Slater-type functions of angular momentum up to L = 1. The exponents of the Slater-type functions are obtained using a divide-and-conquer method to avoid the curse of dimensionality that otherwise is present for large nonlinear optimizations. A Levenberg-Marquardt algorithm is applied in the fitting process. A set of parameters is obtained for each molecule, and the process is fully automated. Calculations have been performed in the carbon monoxide and the water dimers to illustrate the model. Results show a very good accuracy of the model with relative errors in the electrostatic potential lower than 3% over all reasonable separations. At very short distances where the charge overlaps is the most significant, errors are lower than 8% and lower than 3.5% at distances near the van der Waals minimum.

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Contribution to journal
publication status
published
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in
Journal of Chemical Theory and Computation
volume
12
issue
5
pages
14 pages
publisher
The American Chemical Society
external identifiers
  • scopus:84973176420
  • wos:000375810000018
ISSN
1549-9618
DOI
10.1021/acs.jctc.5b01155
language
English
LU publication?
yes
id
b26fdf0c-3c0f-43f9-9b83-a36236ce295b
date added to LUP
2017-02-01 10:56:09
date last changed
2017-09-18 11:35:04
@article{b26fdf0c-3c0f-43f9-9b83-a36236ce295b,
  abstract     = {<p>The effects of charge overlap, or charge penetration, are neglected in most force fields and interaction terms in QM/MM methods. The effects are however significant at intermolecular distances near the van der Waals minimum. In the present study, we propose a method to evaluate the intermolecular Coloumb interaction using Slater-type functions, thus explicitly modeling the charge overlap. The computational cost of the method is low, which allows it to be used in large systems with most force fields as well as in QM/MM schemes. The charge distribution is modeled as a distributed multipole expansion up to quadrupole and Slater-type functions of angular momentum up to L = 1. The exponents of the Slater-type functions are obtained using a divide-and-conquer method to avoid the curse of dimensionality that otherwise is present for large nonlinear optimizations. A Levenberg-Marquardt algorithm is applied in the fitting process. A set of parameters is obtained for each molecule, and the process is fully automated. Calculations have been performed in the carbon monoxide and the water dimers to illustrate the model. Results show a very good accuracy of the model with relative errors in the electrostatic potential lower than 3% over all reasonable separations. At very short distances where the charge overlaps is the most significant, errors are lower than 8% and lower than 3.5% at distances near the van der Waals minimum.</p>},
  author       = {Öhrn, Anders and Hermida-Ramon, Jose M. and Karlström, Gunnar},
  issn         = {1549-9618},
  language     = {eng},
  month        = {05},
  number       = {5},
  pages        = {2298--2311},
  publisher    = {The American Chemical Society},
  series       = {Journal of Chemical Theory and Computation},
  title        = {Method for Slater-Type Density Fitting for Intermolecular Electrostatic Interactions with Charge Overlap. I. the Model},
  url          = {http://dx.doi.org/10.1021/acs.jctc.5b01155},
  volume       = {12},
  year         = {2016},
}