Transport Parameters for Combustion Species Based on cAMOEBA Polarizable Force Field

In this study, we report a simplified yet accurate generalAMOEBApolarizable force field for combustion-interested molecular species,denoted as Combustion-AMOEBA or cAMOEBA. By eliminating the permanentatomic dipoles and quadrupoles, retaining the explicit polarizationand defining the general atom types of each molecule species, includingalkanes, alkenes, alkynes, alcohols, peroxides, and aldehydes, a simplifiedand general cAMOEBA force field was constructed and validated usingthe benchmark results obtained at the QCISD-(T)/CBS level of theory.In this way, the tedious parametrization step for permanent atomicmultipoles of each new molecule in the original AMOEBA (Poltype/MP2) force field could be avoided, hence providing the capabilityof accurate high-throughput calculation for a large number of moleculesat lower computational cost. The averaged difference between the calculatedtransport parameters, sigma and epsilon, for approximately 100 differentmolecules and four bath gases (He, Ne, Ar, and N-2) usingcAMOEBA and AMOEBA (Poltype/MP2) are of 0.09% and 1.27%,respectively, showing a good consistence of the general cAMOEBA forcefield with the original AMOEBA (Poltype/MP2) force fieldwhere the multipole force field parameters were obtained from quantummechanical calculation for each small molecule. Our results also indicatedthat the Lorentz-Berthelot combination rule was more applicable thanWaldman-Hagler for obtaining the molecular Lennard-Jones parametersof pure gases from one bath gas, while the Waldman-Hagler combinationrule was better for obtaining such parameters from all four bath gases.The pure gas parameters obtained using cAMOEBA can be applied to develophigh quality transport property database for combustion modeling.

Automated summary

In this study, a simplified and accurate general AMOEBA polarizable force field called Combustion-AMOEBA or cAMOEBA is reported. The cAMOEBA force field eliminates permanent atomic dipoles and quadrupoles, retains explicit polarization, and defines general atom types for different molecular species. It avoids the tedious parameterization process for new molecules in the original AMOEBA force field, enabling efficient high-throughput calculations for a large number of molecules. The cAMOEBA force field shows good consistency with the original AMOEBA force field, and its parameters can be used to develop a high-quality transport property database for combustion modeling.