尿素分子振动光谱的密度泛函理论研究

Theoretical Studies on Vibrational Spectra of Urea

用密度泛函理论方法 BLYP/6-31 1 ++G( 2 df ,2 pd)对尿素分子的平衡几何构型进行了优化 ,并计算了该分子的谐力场 .使用 Wilson的 GF矩阵方法 ,对尿素分子的振动基频进行了理论研究 .根据振动频率的势能分布对此分子的振动基频进行了理论归属 。

The optimized geometries, vibrational force fields and infrared intensities of the urea molecule were calculated by density functional theory method(DFT) with 6\|311++G(\%2df,2pd\%) basis set. The theoretical force field was scaled by using the scaled quantum mechanical force field method with only two scale factors. The root mean square error was found to be 14 cm\+\{-1\} for urea. The assignment of the fundamentals for CO(NH\-2)\-2 and its deuterated isotopomer CO(ND\-2)\-2 were also performed according to the potential energy distributions.