AMBER-ii: New Combining Rules and Force Field for Perfluoroalkanes

A molecular mechanics force field
of the AMBER/OPLS family for
perfluoroalkanes, noble gases, and their mixtures with alkanes has
been proposed. We had to abandon the traditional Lorentz–Berthelot
combining rules for the Lennard-Jones potential to be able to uniformly
describe these substance classes and their mixtures. Instead, the
Waldman-Hagler rules developed for noble gases were used for all of
these elements except hydrogen. Hydrogen is considered to be a particular
substance to which the usual Lorentz–Berthelot rules are applied.
The proposed rules have little effect on the organic chemistry of
H, C, N, and O elements but make it compliant with the chemistry of
heavy elements. Because of assigning a relatively high partial charge
of −0.37e to fluorine atoms, the new force
field reproduces the mutual insolubility of higher liquid alkanes
and perfluoroalkanes.

本研究提出了适用于全氟烷烃、稀有气体及其与烷烃混合物的 AMBER/OPLS 家族分子力学力场。鉴于需统一描述这些物质类别及其混合物，我们不得不摒弃传统的 Lorentz-Berthelot 结合规则以适用于 Lennard-Jones 势。因此，我们采用了专为稀有气体开发的 Waldman-Hagler 规则，适用于除氢以外的所有这些元素。氢被认为是一种特殊的物质，对其适用常规的 Lorentz-Berthelot 规则。所提出的规则对 H、C、N 和 O 元素的有机化学影响微乎其微，但使得力场与重元素化学相吻合。由于对氟原子赋予相对较高的部分电荷（-0.37e），新的力场能够再现高液态烷烃与全氟烷烃的互溶性。