胞嘧啶-水分子氢键团簇结构特性理论研究
The Theoretical Study on Cytosine-water Molecules Hydrogen-bonded Clusters

使用密度泛函理论B3LYP方法，在6-311++G(d , p)基组水平上，研究了C4H5N3O？(H2O)n (n=1~3)分子团簇的基态结构及红外线光谱。通过对C4H5N3O？(H2O)n (n=1~3)分子团簇结构优化，获得了团簇的六种稳定结构。三种最稳定结构的分子团簇的红外光谱表明O―H…O和N―H…O氢键的形成使得O―H和N―H之间伸缩频率减小，发生了红移； O―H…N氢键使O―H之间的伸缩振动频率变大，发生了蓝移。AIM程序分析表明：电子密度的强弱反映了红移和蓝移的大小。之后使用Veda4软件对C4H5N3O？(H2O)n (n=1~3)分子团簇红外光谱的振动频率进行了分析，并对振动频率进行了比较。
The ground state structures and infrared spectra of the C4H5N3O？(H2O)n (n=1~3) clusters are calculated by density functional theory (DFT) at the B3LYP complex function. The six stable structures of C4H5N3O？(H2O)n clusters can be obtained by optimizing the structure. The infrared spectra of the three most stable clusters molecules show that the formation of O―H…O or N―H…O H-bond makes the vibration frequency between O―H or N―H decrease and leads to the vibration frequency red-shifted, while O―H…N H-bond makes the vibration frequency between O―H increase and leads to the vibration frequency blue-shifted. AIM analysis suggests that the electron density that reflects the strength of a bond has been used to explain the red and blue-shifted. The vibrational infrared spectra of C4H5N3O？(H2O)n (n=1~3) clusters are analyzed by using the Veda4 and the vibration frequencies are compared.