鸟嘌呤红外光谱的密度泛函理论研究──标度量子力学(SQM)力场处理  

Density Functional Theory Studies on Molecular Structure and IR Spectra of GuanineA Scaled Quantum Mechanical Force Field Approach

作　　者：薛英[1] 徐定国[1] 谢代前[1] 鄢国森[1] 

机构地区：[1]四川大学化学系,成都610064

出　　处：《高等学校化学学报》2000年第8期1293-1298,共6页Chemical Journal of Chinese Universities

基　　金：国家自然科学基金! (批准号 :2 9892 162 );高等学校博士学科点专项基金

摘　　要：用密度泛函理论 DFT( B3 LYP) /6-3 1 G* 方法对鸟嘌呤分子的酮 -胺式和醇 -胺式异构体的几何结构、振动谐性力场和红外光谱进行了研究 .理论力场由迁移自相关分子异胞嘧啶和咪唑的力常数标度因子进行标度 .算得振动频率与鸟嘌呤的实验基质隔离 IR光谱比较平均偏差对酮 -胺式和醇 -胺式分别为 6.6和 6.0cm- 1 .根据振动频率的势能分布和Density functional theory with the combined Becke 3 LYP exchange correlation energy function using the 6 31G * basis set was applied to study the structures and vibrational IR spectra of amino oxo and amino hydroxy forms of guanine. The calculated force fields were corrected by scaling the forces fields over a convenient set of local internal coordinates. The scale factors were determined by least squares fitting of the theoretical frequencies to the experimental ones of the two parent molecules, isocytosine and imidazole. The predicted vibrational frequencies of two tautomers of guanine were compared with the available observed matrix isolated IR spectra with mean deviations of about 6.6 cm -1 for amino oxo form and 6.0 cm -1 for amino hydroxy form. The results made it possible to give reliable assignments of the IR spectra of isolated guanine. This study shows that the scaled density functional force field approach enables us to give a good interpretation of vibrational spectra of large molecules through the transferability of scale factors.

关 键 词：鸟嘌呤 DFT计算 SQM力场 红外光谱 结构 

分 类 号：Q526.01[生物学—生物化学] O641.121[理学—物理化学]