水蒸气分子在金属钚表面吸附的量子力学计算

Adsorption Study of Water Vapor Molecule on Metal Pu Surface by Quantum Mechanism Computation

采用密度泛函理论(B3LYP)方法,钚原子采用相对论有效原子实势(RECP)SDD基组,氢、氧原子采用aug-cc-pVTZ全电子基组,优化了PuO2的分子结构,得到了相应的平衡几何构型。同时优化了Pu—H2O的4个稳定异构体。比较能量发现水分子易于解离,从而与Pu形成更稳定的结构。由于Pu与O原子的电负性相差很大易发生电荷转移,分子的稳定性主要源于Pu—O之间的相互作用。根据电子-振动近似理论,计算了不同温度下金属Pu与H2O吸附与解离反应的生成热力学函数。计算表明,即使在低温下,H2O蒸汽分子也无法在金属钚表面形成分子吸附,相反,在金属钚表面水分子的解离可自发进行。

Employing density functional method(B3LYP) with the relativistic effective core potential(RECP) for Pu atom and all-electron basis set aug-cc-pVTZ for O and H atoms,the equilibrium geometrical structures of PuO2 molecule were optimized.In addition,four structures for Pu-water were proposed and studied.The results indicate that water molecule tends to dissociate to form more stable structure with Pu.Due to the lager difference of electronegativity for Pu and O atoms,the stable structure is from the interaction of Pu and O atoms.The thermodynamic functions of adsorption and dissociation reactions of Pu and H2O were calculated according to electronic-vibration approximation.The results show that the water vapor molecule can’t adsorb on Pu surface even at low temperature,in contrast,dissociation reactions of H2O on Pu surface can occur spontaneously.