Al_2O_3 X(X=H,D,T)的电子振动近似理论方法研究  

Electron-vibration approximation method for hydrogen isotope compounds Al_2O_3 X(X=H,D,T)

作　　者：谌晓洪[1] 王玲[1] 朱正和[2] 罗顺忠[3] 

机构地区：[1]西华大学理化学院,成都610039 [2]四川大学原子与分子物理研究所,成都610065 [3]中国工程物理研究院核物理与化学研究所,绵阳621900

出　　处：《物理学报》2007年第8期4467-4476,共10页Acta Physica Sinica

基　　金：中国工程物理研究院科研基金重大项目(批准号:2003Z0501);国家自然科学基金(批准号:10376022);西华大学人才培养基金(批准号:R0723314)资助的课题.~~

摘　　要：用密度泛函理论(DFT)方法在6-311++G(d,p)水平上对Al2O3X(X=H,D,T)分子较低能量的几何构型进行了优化.计算结果表明该分子有两个可能基态,即Al2O3X(X=H,D,T)(2A′)Cs和Al2O3X(X=H,D,T)(2B2)C2v.全电子计算了氢同位素分子及Al2O3X(X=H,D,T)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Al2O3X(X=H,D,T)中的电子和振动能量和熵近似代表它们处于固态时的能量和熵,计算得到固体Al2O3的氢化热力学函数ΔH0,ΔS0,ΔG0以及平衡压力与温度的关系.当Al2O3吸附氢(氘,氚)形成C2v对称性气态Al2O3X(X=H,D,T)对应的固体时,氢气可以排代氘气,氘气可以排代氚气.这种排代效应非常不明显;形成Cs对称性气态Al2O3X(X=H,D,T)对应的固体时,反应的氢氘氚排代效应的顺序为氚排代氘,氘排代氢,与钛等的氢氘氚排代效应的顺序相反.总体而言,这种排代效应都非常弱.随着温度的增加,这一系列反应的氢氘氚排代效应趋于消失.The geometric configuration, vibration frequency and thermodynamic properties of Al2O3X （X = H, D, T） molecular clusters with lower energy were optimized using B3LYP/6-311 ＋ ＋ G（ d, p） method. The changes of entropy, enthalpy and Gibbs free energy of the reactions between Al2O3 and hydrogen （deuterium or tritium） gas have been calculated under the solid electrorrvibration approximation method using formulae in thermodynamics under temperatures of 298-1098 K. Then the equilibrium pressures of hydrogen （deuterium or tritium） gas in these reactions are obtained. The results show that, the gaseous Al2O3 X may have two possible ground states Al2O3X（X = H,D,T）（^2A＇） Cs and Al2O3 X （^2B2） C2v. Tritium can be displaced by deuterium; deuterium can be displaced by hydrogen in the reactions between Al2O3 and X2 with the production of solid Al2O3X which relates to ground Al2O3 X with C2v symmetry. This displacement sequence is the same as that in the reactions between titanium and X2 . These displacement effects are very weak. But hydrogen can be displaced by deuterium; deuterium can be displaced by tritium in the reactions between Al2O3 and X2 with the production of solid A12O3 X which relates to ground gaseous Al2O3 X with Cs symmetry. This displacement sequence is opposite to that in the reactions between titanium and X2 . In all, these displacement effects are very weak, and they grow still weaker as the temperature increases.

关 键 词：Al2O3X(X=H D T)分子团簇 热力学函数 氢同位素效应 吉布斯自由能改变 

分 类 号：O561.1[理学—原子与分子物理]