摘要
本文利用B3LYP的密度泛函方法对PdY、PdYH的分子结构进行了优化 ,得到PdY最稳定的电子态为 2 Σ ,RPdY =0 .2 4 1 8nm ,ωe =2 4 9.6 6cm-1 ,De =2 .75eV。PdYH最稳定构型为CS,1 A′态 ,RPdY =0 .2 4 3 0nm ,RYH =0 .1 974nm ,∠PdYH =1 1 6 .5 4° ,谐振频率ν1 (a′) =1 4 5 0 .83cm-1 ,ν2 (a′) =3 5 1 .2 1cm-1 ,ν3(a′) =2 4 3 .71cm-1 ,离解能De(PdYH)为 5 .6 4eV。并以气态分子总能量中的振动能Ev代替分子处于固态时的振动能 ,以电子运动和振动运动熵SEv代替分子处于固态的熵的近似方法计算了PdY与氢及其同位素反应的ΔHθ、ΔSθ、ΔGθ 及氢化反应平衡压力 ,得出PdYH(S)的生成焓为 6 0 .3 2kJ·mol-1 。
The structures of PdY and PdYH have been optimized by density functional theory (B3LYP) and Relativistic Effective Core Potential (RECP) method. The results show that the ground states for PdY and PdYH are of ()~2Σ and ()~1A′ symmetry respectively. For PdY molecule, the bond length (R_(PdY)) is 0.241 8 nm, and the harmonic frequency (ω_e) and the dissociation energy (D_e) are 249.66 cm^(-1) and 2.75?eV respectively. For PdYH molecule, the structure parameters R_(PdY), R_(YH) and ∠PdYH are 0.243 0 nm, (0.197 4) nm and 116.54° respectively, and the dissociation energy (D_e(PdYH)) is 5.64 eV and the vibrational frequencies are 1 450.83 cm^(-1), 351.21?cm^(-1) and 243.71 cm^(-1). Furthermore, to calculate enthalpy H and entropy S of solid PdYH, PdYD and PdYT, the vibrational energy or electronic and vibration entropy of the molecules are assumed to be the corresponding values of their solid states. The thermodynamic function ΔH~θ,ΔS~θ,ΔG~θ of PdYH、PdYD and PdYT have also been calculated by this approximation method, and based on this results, the present have obtained hydrogen isotope equilibrium pressure of the hydrogenating reaction. The enthalpy of formation of PdYH(s) is 60.32kJ·mol^(-1) at 298.15 K.
出处
《原子与分子物理学报》
CAS
CSCD
北大核心
2005年第1期77-82,共6页
Journal of Atomic and Molecular Physics
基金
国家自然科学基金委-中国工程物理研究院联合基金 (NO .1 0 1 76 0 2 1 )
关键词
PdY合金
密度泛函理论
分子结构
热力学函数
PdY alloy
Density functional theory
Molecular structure
Thermodynamic function
