氢同位素化合物TiH_2,TiD_2和TiT_2的电子振动近似理论方法

Electron-vibration approximation method for hydrogen isotope compounds TiH_2,TiD_2 and TiT_2

根据原子分子反应静力学和群论,确定TiH2,TiD2和TiT2的基电子状态为3A2.应用基函数6-311G**和密度泛函理论B3P86方法,全电子计算了氢同位素分子及其钛化物的能量E、定容热容Cv和熵S.应用电子振动近似理论,即用单个分子TiH2,TiD2和TiT2中的电子和振动能量和熵近似代表他们处于固态时的能量和熵.计算所得到的金属钛的氢化热力学函数ΔH0,ΔS0,ΔG0以及平衡压力与温度的关系,与文献符合很好,这表明电子振动近似理论的可应用性,选用金属钛作为中子靶是很正确的.

The ground states of TiH2 ,TIDE and TiT2 are determined as ^3A2 based on atomic and molecular statics and ground theory. The energy E, heat capacity Cv and entropy S of hydrogen isotopic molecules and its titanium compounds have been calculated using density functional theory （DFT） with basis set 6-311G^＊＊ . The electronic and vibrational energy and entropy of single molecules TiH2, TiDE and TiT2 are used as the energy and entropy in their solid states approximately, which is called the electro,vibration motion approximation theory （EVMAT）. The calculated results of hydrogenation （and of its isotopes ） thermodymical functions △Hc^0,△S^0,△G^0 and equilibrium pressure of metallic titanium changing with temperature are in good agreement with experimental data, which confirms EVMAT theory further.