Accurate Calculation of Hydration Free Energies using Pair-Specific Lennard-Jones Parameters in the CHARMM Drude Polarizable Force Field.

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TitleAccurate Calculation of Hydration Free Energies using Pair-Specific Lennard-Jones Parameters in the CHARMM Drude Polarizable Force Field.
Publication TypeJournal Article
Year of Publication2010
AuthorsBaker, CM, Lopes, PEM, Zhu, X, Roux, B, Mackerell, AD
JournalJ Chem Theory Comput
Volume6
Issue4
Pagination1181-1198
Date Published2010 Mar 01
ISSN1549-9626
Abstract

Lennard-Jones (LJ) parameters for a variety of model compounds have previously been optimized within the CHARMM Drude polarizable force field to reproduce accurately pure liquid phase thermodynamic properties as well as additional target data. While the polarizable force field resulting from this optimization procedure has been shown to satisfactorily reproduce a wide range of experimental reference data across numerous series of small molecules, a slight but systematic overestimate of the hydration free energies has also been noted. Here, the reproduction of experimental hydration free energies is greatly improved by the introduction of pair-specific LJ parameters between solute heavy atoms and water oxygen atoms that override the standard LJ parameters obtained from combining rules. The changes are small and a systematic protocol is developed for the optimization of pair-specific LJ parameters and applied to the development of pair-specific LJ parameters for alkanes, alcohols and ethers. The resulting parameters not only yield hydration free energies in good agreement with experimental values, but also provide a framework upon which other pair-specific LJ parameters can be added as new compounds are parametrized within the CHARMM Drude polarizable force field. Detailed analysis of the contributions to the hydration free energies reveals that the dispersion interaction is the main source of the systematic errors in the hydration free energies. This information suggests that the systematic error may result from problems with the LJ combining rules and is combined with analysis of the pair-specific LJ parameters obtained in this work to identify a preliminary improved combining rule.

DOI10.1021/ct9005773
Alternate JournalJ Chem Theory Comput
PubMed ID20401166
PubMed Central IDPMC2853947
Grant ListR01 GM072558 / GM / NIGMS NIH HHS / United States
R01 GM072558-06 / GM / NIGMS NIH HHS / United States
R01 GM051501-13 / GM / NIGMS NIH HHS / United States
R01 GM051501 / GM / NIGMS NIH HHS / United States
R29 GM051501 / GM / NIGMS NIH HHS / United States