甘氨酸晶体结构和振动频率的密度泛函方法研究

用密度泛函理论(DFT)的BLYP、B3LYP、Hartree-Fock(HF)和MP2方法,在6-311 G**基组水平上,对甘氨酸的几何构型和红外光谱进行了研究,并与实验结果(晶体数据)作了比较,得出了以上方法在计算甘氨酸的几何参数和谐振频率与实验数据间的相关性:在优化几何参数方面,B3LYP方法优于其它方法;在计算振动频率方面,可以看出对HF方法,标度因子校正是必要的,在非校正的情况下,DFT方法优于MP2和HF方法.

Structure and Vibrational Frequencies of Glycine Crystal: a Density Functional Theoretical Study

In this paper,the geometry structures and infrared spectrum of glycine have been calculated using density functional theory(BLYP,B3LYP) at the basis set of 6-311 G**(d,p),the calculations also have been carried out using HF(Hartree-Fock) and MP2 methods at the same basis set level.The relation between the geometry parameters,vibriation frequencies and experimental datas(crystal datas) are investigated,by comparing the calculated results with experiments.The B3LYP is believed to give the more reliable optimizing structures,and for HF method,it is necessary to adjust vibrational frequencies by using scaled factors;the DFT method is superior to MP2 and HF methods in the unscaled condition.