中文摘要：

用密度泛函理论的B3LYP方法，对钯原子采用LANL2DZ收缩价基函数，碳原子和氧原子采用AUG-cc-pVTZ基组，对PdC，PdO和PdCO体系的结构进行优化，计算表明：PdC分子基态为^1∑^＋态，键长为Re=0．17285nm，离解能为4．919eV．PdO分子基态的平衡核间距为0．18546nm，其电子态为^3Ⅱ，离解能为2．455eV，并拟合得到Murrell-Sorbie势能函数；PdCO分子有两个线性稳定构型，其中一个构型为Pd-c≡0（C∞v），电子态为^1∑^＋，平衡核间距为Rpdc=0．18721nm，Rco=0．11427nm，离解能为12．563eV，另一个为Pd-0≡C（C∞v），电子态是^1∑^＋，平衡核间距为Rco=0．11336nm，Rpdo=0．23001nm，离解能为10．937eV。由微观过程的可逆性原理分析了分子的可能的离解极限，并用多体展式理论导出基态PdCO分子的势能函数，其等势面图准确地再现了PdCO分子的结构特征和离解能，由此讨论了Pd＋CO，PdC＋O，PdO＋C分子反应的势能面静态特征。

英文摘要：

Density functional method（B3LPY） has been used to optimize the possible structures of PdC, PdO and PdCO molecules with contracted valence basis set （LANL2DZ） for Pd atom and the AUG-cc-pVTZ basis set for C and O atoms respectively. It was found that the ground state of PdC molecule is ^1∑, whose equilibrium nuclear distance and dissociation energy are Rpdc=0.17285 nm and 4.919eV, respectively. The ground state of PdO molecule is ^3Ⅱ with equilibrium geometry Rpdo=0.18546 nm and dissociation energy De=2.455 eV. The ground state of the linear Pd-C≡O（C∞v） is ^1∑^＋ and the configuration and dissociation energy are Rpdc=0.18721 nm, Rco =0.11427 nm and 12.563 eV, respectively. At the same time, another metastable structure Pd-O≡ C（ C∞v ） was found. Its equilibrium geometry and dissociation energy are Rco = 0. 11336 nm, Rpdo = 0.23001 nm and 10.937 eV, respectively .The possible dissociation limit of PdCO molecule is determined.The analytical potential energy function for PdCO molecule has been obtained from the many-body expansion theory. The contour of the potential energy surface sheds light on the accurate structure and dissociative energy for PdCO molecule. Furthermore, the molecular static reaction pathway based on this potential energy function is investigated.