氨基酸分子的光学活性和频效应

摘要

用带限制场Hartree-Fock (RHF/6-311++G**)从头算的方法进行分子构型优化，单激发态组态相互作用(CIS/6-311++G**)计算各种需要的相关数据；应用态求和理论，以长度偶极矩和速度偶极矩两种形式模拟了一系列氨基酸离子的光学活性和频效应(OA-SFG)光谱。结果表明速度偶极矩计算得到的一系列氨基酸离子的和频效应光谱强度顺序能很好地与实验相吻合，而长度偶极矩形式计算得到的结果与实验不吻合。引起这两种形式和频效应光谱理论计算结果差别的原因是由于长度偶极矩形式具有原点敏感性，而速度偶极矩没有。速度偶极矩方法更适用于分子光学活性和频效应的模拟。%Optical y active sum frequency generation (OA-SFG) spectra of a series of chiral amino acid molecules are simulated with the dipole length and dipole velocity formalisms using the sum-over-states theory based on ab initio restricted Hartree-Fock (RHF/6-311++G**) and configuration interaction singles (CIS/6-311++G**) quantum chemistry calculations. OA-SFG spectra calculated by the dipole velocity method accurately reproduce the experimental relative intensity of OA-SFG spectra of amino acids, but the dipole length simulation did not. This is because of the origin-sensitivity of dipole length formulations. This study shows that it is preferable to use the dipole velocity method over the dipole length method to simulate OA-SFG spectra.