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Internet Electronic Journal of Molecular Design - IEJMD, ISSN 1538-6414, CODEN IEJMAT
| ABSTRACT - Internet Electron. J. Mol. Des. April 2008, Volume 7, Number 4, 77-87 |
Application of the Four-Parameter Diatomic Potential in Molecular Mechanics Force Fields
Teik-Cheng Lim
Internet Electron. J. Mol. Des. 2008, 7, 77-87
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Abstract:
Parameters from a four-parameter diatomic potential (FPDP) are herein converted
into Morse parameters for application in molecular mechanics force fields that
adopt the Morse potential for describing the bond-stretching energy. Three
methods for converting the FPDP parameters, i.e. (a) imposition of equal bond
stiffness, (b) imposition of equal equilibrium-to-dissociation energy integral, and
(c) imposition of equal limits of bond dissociation, give the Morse shape
parameter for near, intermediate and far range respectively. The validity of these
methods has been supported through comparison of FPDP energy and the Morse
energy using FPDP parameters. Because FPDP can be converted into the Morse
potential, it is possible to use FPDP parameters for Morse potential. This property
may be applied to molecular mechanics code that use Morse potential to increase
the accuracy of the bond-stretching energy without drastic change in the source
code. The use of three Morse shape parameters for various dimensionless bond
length (r/R) ranges enables the FPDP accuracy to be approached by the Morse function.
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