复合物M-cytosine（M=Ca^＋、Ca^2＋、Mg^＋和Mg^2＋）的振动分析

采用密度函数理论的Becke三参数交换能和LYP关联能混和泛函B3LYP,在6-311＋G（2df,2p）基组水平上,优化获得了钙、镁的一、二价离子与胞嘧啶分子的各互变异构体形成复合物稳定结构,并在此基础上进行频率计算。根据计算结果,对比分析了一、二价钙、镁离子与相同嘧啶分子形成稳定复合物的振动情况。从分析结果看,由于离子的作用,振动特征会发生相应的变化,主要表现在与离子直接作用的那个原子在参与环的振动时,频率和振幅都发生变化,产生这种变化的原因是由于离子与单体嘧啶分子的不同位置作用,改变了单体分子的作用力常数和质量因素,引起振动模式的改变,从而改变振动特征。

Frequency analysis of complexes M-cytosine（M=Ca^＋,Ca^2＋,Mg^＋ and Mg^2＋）

The complexes stable structures were obtained, which were composed of calcium and magnesium bivalent cations and cytosine, by the optimization with density function theory at the B3LYP/6-311 ＋ G（2df,2p） level. The vibrational frequency was calculated, and the atoms vibration was analyzed. Some vibration modes belonging to the obvious frequencies of the complexes were discussed. According to the results, the frequencies obviously changed when the pyrimidine monomer acted with the cations. This mainly because the cations could take part in the molecule＇s vibrations and change the force constants and effective mass.