PtCO分子结构与解析势能函数

The molecule structure and potential energy function of PtCO

用密度泛函理论的B3P86方法,对铂原子采用LANL2DZ收缩价基函数,碳原子和氧原子采用6-311G*基组,对PtC,PtO和PtCO体系的结构进行优化,计算表明:PtC分子基态为~1∑^+态,键长为Re=0.16844 nm,离解能为6.31435 eV.PrO分子基态的平衡核间距为0.17486 nm,其电子态为~3∑^-,离解能为3.84565 eV,拟合得到Murrell-Sorbie势能函数;PtCO分子有两个线性稳定构型,其中一个构型为Pt-C(?)O(C_(∞v)),电子态为~1∑^+,平衡核间距为R_(PtC)=0.17672 nm,R_(CO)=0.11464 nm,离解能为14.46769 eV,另一个为Pt-O(?)C(C_(∞v)),电子态是~1∑^+,平衡核间距为R_(CO)=0.11243 nm,R_(PtO)=0.21886 nm,离解能为11.26729 eV.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PtCO分子的势能函数,其等势面图准确地再现了PtCO分子的结构特征和离解能,由此讨论了Pt+CO,PtC+O,PtO+C分子反应的势能面静态特征.

Density functional theory （DFT） B3P86 have been used to calculate the equilibrium geometries and vibrational properties of the possible structures and electronic states of PtC, PrO and PtCO molecules with contracted valence basis set （LANL2DZ） for Pt atom and 6-311G＊ for C and O atoms respectively. The present computational results predict that the ground electronic state of PtC is 1 ∑＋ with equilibrium geometry Re=0. 16844 nm and the dissociation energy is 6. 31435 eV. Similarly, the ground electronic state of PtO is 3 ∑- with eqailibrium geometry Re= 0. 17486 nm and the dissociation energy is 3. 84565 eV. The ground electronic state of Pt--C≡O is 1 ∑＋ （C∞v） with equilibrium geometries RptC= 0. 17672 nm,Rco=0. 11464 nm and the dissociation energy is 14. 46769 eV. At the same time, another metastable structure Pt-O≡-C is found. Its equilibrium geometry and dissociation energy are Rco= 0. 11243 nm,Rpto = 0. 21886 nm and 11. 26729 eV, respectively. Then, the analytic potential energy function of PtCO molecule is derived by many-body expansion theory for the first time. The contours ofthe poter, tial energy surface are constructed, which clearly reproduce the character of the accurate structure and dissociation energy for PtCO molecule. Furthermore, the molecular static reaction pathways based on this potential energy function are investigated.