Geometry Predictions,Vibrational Analysis and IR Intensities of XH3Y(X=C,Si,Ge,Y=F,Cl,Br) Calculated by Hybrid Density Functional Theory,MP2 and MP4 Methods

摘要

Hybrid density functional theory B3LYP,B1LYP,B3P86,MPW1PW91 and B3PW91 methods as well as MP2 and MP4 methods at the 6-311++G(3df,3pd)level of theory are used for the calculations of geometrical parameters,infrared vibrational frequencies and absorption intensities of XH3Y(X=C,Si,Ge and Y=F,Cl,Br)set of molecules.All of the calculated results are compared with the most recent experimental data.The advantages of DFT methods are exhibited from the comparison and discussion.The basis set effect is also considered and the optimal theoretical methods for the discussed systems are recommended.