中文摘要：

本文以蓝藻内特殊的色素蛋白一藻胆蛋白（phycobiliprotein，Pc）为研究对象，首先对生物大分子PC几何结构进行优化简化，对该分子的频率进行了计算，并没有出现虚频。采用半经验方法（modified neglect of diatomic overlap parametric method 3，PM3）、从头算法（hartree—fock，HF）、密度泛函法（density functional theory，DFT）分别计算了PC简化分子的能量、紫外光谱、红外光谱。结果显示活性基团的相对位置与实测值较接近，证明理论计算值接近真实情况。

英文摘要：

Phycobiliprotein （PC） is a special pigment-protein in cyanobacteria. In this study, the geometric structure of this typical biological macromolecule PC was optimized and simplified firstly. Then by calculating the frequency of the molecule, no imaginary frequency appeared. The energy, ultraviolet spectroscopy, and infrared spectroscopy （IR） of the simplified PC molecule were calculated using the modified neglect of diatomic overlap parametric method 3 （PM3）, hartree-fock （HF） and density functional theory （DFr） respectively. The results showed that the relative positions of active groups were approaching to the actual measured positions, and this proved that the calculated values were close to actual values.