Polarizable force field for water-dimethyl sulfoxide systems: I Parameterization and gas phase test

A new polarizable, flexible force field for dimethyl sulfoxide (DMSO) was developed to study the properties of DMSO-Water systems. The charge-related parameters of DMSO molecule (atomic valence-state hardness and negativity) were well derived from ab initio (B3LYP/6-311++G (2d, p)) charge responses. The perturbed external field were generated by the “massless TIP4P-FQ water” in order to be consistent with TIP4P-FQ water force field. The polarized behaviors of DMSO molecule under the external fields in gas phase can be well described by the current model and parameters. The DMSO-FQ model can provide a reasonable representation of the induced dipole for DMSO molecule in DMSO-water clusters. The energetic and structural properties of DMSO-water clusters in gas-phase have been studied by DFT and the polarizable force field developed here. The hydrogen bond lengths, binding energies and many-body energies of a series of DMSO-Water clusters calculated by the high level ab initio methods are well reproduced by the current model.