Molecular Dynamic Simulations For Infrared Absorption Spectrum Of Organic Small Molecular Liquids

In the thesis, we firstly make a brief introduction about the molecular dynamic simulations and other its relevant knowledge in the first section. We also present that the conditions to generating and present the difference between the models of the traditional force field and polarizable force field. Specially, we underline for the AMOEBA polarizable force field. Through discussion aforementioned, one learns that the efficiency of the molecular dynamic simulation depends on the qualitative property of force field. Besides, the conditions to generating the infrared absorption spectrum are also introduced.Next we describe detailed the concrete steps and smarts about the usage of Tinker package. The molecular dynamic simulations of water, methanol and ethanol have been carried out within the AMOEBA polarizable force filed, and their infrared spectrums are analyzed as well as compared with the simulation results with traditional force field. The results show that the simulations with AMOEBA force field are better agreement with the experimental than those of other traditional force field. The dominant reason is that AMOEBA force field including the effect from the electric multipole moment and the induced dipole moment; hence the electrostatic interaction is described accurately. So it is better to calculate the bending vibration and the stretching vibration of chemical bonds. Finally, the molecular dynamic simulations of benzene and phenol with different dominant modes have been carried out to study their infrared spectrum. The part of research work needs more experiments and more detailed theoretical study in future.