【摘要】 采用密度泛函方法和相对论有效原子实势分别对PdCO、PdOC及PdH的几何构型进行了优化,得到PdCO和PdOC分子电子状态均为（X¹ ∑⁺）,对于PdCO分子,R_PdC=0.1834 nm,R_CO=0.1140 nm,∠PdCO=180°;对于PdOC分子,R_PdO=0.2157 nm,R_CO=0.1133,nm,∠PdOC=180°;PdH分子基态为²∑,R_PdH=0.1526 nm。根据电子-振动近似理论计算了不同温度下金属Pd与CO及H₂分子反应的生成热力学函数,导出了反应平衡压力随温度的变化关系,分析认为CO引起Pd合金膜中毒主要是由于CO的C原子与Pd原子结合而使CO分子吸附在膜表面所致。更多还原

【Abstract】 The different structures of PdCO, PdOC, and PdH were optimized by the relativistic effective core potential （RECP） and the density functional method B3P86. The results showed that Pd and CO of stable Pd—CO molecule were in the same plane. The ground state of PdCO was （X¹ ∑⁺） of C_∞v, and the bond length (R_PdC) was 0.1834 nm, (R_CO) was 0.1140 nm, bond angle（∠PdCO）was 180.0°. For PdOC molecule, the ground state was also （X¹ ∑⁺）, the structure parameters R_PdO, R_CO, and ∠PdOC were 0.2157 nm, 0.1133 nm, and 180°, respectively. The ground state of PdH was ²∑, and the bond length was 0.1526 nm. Furthermore, the thermodynamic functions of PdCO, PdOC, and PdH were also calculated according to electronic-vibration approximation, and the relationship of the equilibrium pressures with temperatures was obtained. From the results, it was deduced that the poisoning effect of CO was mainly due to the adsorption of CO on palladium surface by combining C atom with Pd atom.更多还原