In this study, we report a simplified yet accurate general
AMOEBA
polarizable force field for combustion-interested molecular species,
denoted as Combustion-AMOEBA or cAMOEBA. By eliminating the permanent
atomic dipoles and quadrupoles, retaining the explicit polarization
and defining the general atom types of each molecule species, including
alkanes, alkenes, alkynes, alcohols, peroxides, and aldehydes, a simplified
and general cAMOEBA force field was constructed and validated using
the benchmark results obtained at the QCISD(T)/CBS level of theory.
In this way, the tedious parametrization step for permanent atomic
multipoles of each new molecule in the original AMOEBA (Poltype/MP2) force field could be avoided, hence providing the capability
of accurate high-throughput calculation for a large number of molecules
at lower computational cost. The averaged difference between the calculated
transport parameters, σ and ε, for approximately 100 different
molecules and four bath gases (He, Ne, Ar, and N2) using
cAMOEBA and AMOEBA (Poltype/MP2) are of 0.09% and 1.27%,
respectively, showing a good consistence of the general cAMOEBA force
field with the original AMOEBA (Poltype/MP2) force field
where the multipole force field parameters were obtained from quantum
mechanical calculation for each small molecule. Our results also indicated
that the Lorentz-Berthelot combination rule was more applicable than
Waldman-Hagler for obtaining the molecular Lennard-Jones parameters
of pure gases from one bath gas, while the Waldman-Hagler combination
rule was better for obtaining such parameters from all four bath gases.
The pure gas parameters obtained using cAMOEBA can be applied to develop
high quality transport property database for combustion modeling.