To obtain Gay-Berne (GB) parameters, we carried out Monte Carlo sampling of four reference configurations based on the Boltzmann distribution. After comparing with the van der Waals potential within the all-atom model we obtained the GB parameters. Also by fitting the charge, dipole, and quadrupole with the electric potential obtained from quantum chemical computations with Gaussian 03 we obtained the electric multipole potential (EMP) parameters. With the GB-EMP parameters we then carried out molecular dynamics simulations (MDS) for CHCI3 and tetrahydrofuran (THF) based on the coarsegrained (CG) model. Compared with the all-atom model, the CG model can reproduce the simulation results on the whole, but there are some deviations in the simulations in some details. The reason is that we only take one interaction site into account in this work. Therefore, for more complicated molecules it is necessary to take the placement of the interaction sites into account. Additionally, the multi-sites situation is also considered in the MDS within the frame of the coarse-grained model.%在基于Boltzmann分布对四种基本构象进行Monte Carlo取样后,通过与全原子模型的范德华势比较得到了Gay-Beme (GB)参数.又在对用量化计算得到的分子体系的电势进行电荷、偶极矩和四极矩的拟合后,得到了电多极展开势(EMP)参数.利用得到的粗粒化参数,基于粗粒化模型,对CHCl3及四氢呋喃(THF)两种有机溶剂进行了分子动力学模拟(MDS),并将结果同全原子模拟进行了比较.计算结果表明用粗粒化模型从整体上能重复全原子模型的模拟结果,但在某些细节的计算与全原子模型有偏差,其原因可能是目前工作仅考虑了单位点情况,为此今后在对具有复杂结构的分子进行粗粒化模拟时还应考虑合理放置及增加相互作用位点.
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