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Parametrization of aliphatic CH n united atoms of GROMOS96 force field
Author(s) -
Daura Xavier,
Mark Alan E.,
Van Gunsteren Wilfred F.
Publication year - 1998
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/(sici)1096-987x(19980415)19:5<535::aid-jcc6>3.0.co;2-n
Subject(s) - van der waals force , chemistry , van der waals strain , van der waals radius , force field (fiction) , hamaker constant , theorem of corresponding states , london dispersion force , parametrization (atmospheric modeling) , van der waals surface , cutoff , van der waals equation , enthalpy of vaporization , boiling point , thermodynamics , atomic physics , molecule , physics , enthalpy , quantum mechanics , organic chemistry , radiative transfer
The derivation of the van der Waals parameters for the aliphatic CH n united atoms of the GROMOS96 force field is presented. The parameters have been adjusted to reproduce the experimental enthalpies of vaporization and vapor pressures or densities of a set of nine alkanes in the liquid state at 298 K (or at the boiling point in the case of methane), using a cutoff radius for the van der Waals interactions of 1.6 nm. Force fields to be used in molecular simulations are bound to the conditions chosen for their parametrization, for example, the temperature, the densities of the systems included in the calibration set, or the cutoff radius used for the nonbonded interactions. Van der Waals parameters for the CH n united atoms of earlier GROMOS force fields were developed using a cutoff radius of 0.8 nm for the van der Waals interactions. Because the van der Waals interaction energy between aliphatic groups separated by distances between 0.8 and 1.4 nm is not negligible at liquid densities, the use of these parameters in combination with longer cutoffs leads to an overestimation of the attractive van der Waals interaction energy. The relevance of this excess attraction depends on the size of the groups that are interacting, as well as on their local densities. Free energies of hydration have been calculated for five alkanes. © 1998 John Wiley & Sons, Inc. J Comput Chem 19: 535–547, 1998