密度泛函理论研究LiX(X=H,D,T)体系的热力学性质
Thermodynamic properties of LiX(X=H, D, T) system investigated by density-functional theory
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摘要: 运用量子力学从头计算方法，计算了氢化锂（氘化锂、氚化锂）分子的部分热力学函数和力学、光谱学性质。基于准简谐Debye模型，计算了固体Li的振动内能、振动和电子熵，探讨了Li吸收氢同位素气体生成一氢化物的反应熵变、生成焓变和生成Gibbs自由能及氢同位素的平衡离解压。结果显示：在Li吸收同位素气体生成一氢化物的反应中，生成焓变和反应熵变均为负值，且随温度升高，绝对值越大，Gibbs自由能则向正的方向增加。热力学上，在相同温度和压力下，氢置换一氢化物中的氘和氚、及氘置换氚的反应更易发生。Abstract: Some thermodynamic functions, mechanics and spectroscopic properties for LiX(X=H,D,T) were calculated with ab initio method. The vibration energy and vibration entropy for solid Li were calculated based on the quasi-harmonic Debye’s theory. The changes of thermodynamic functions were calculated and discussed, which are the enthalpy, reaction entropy, Gibbs free energy and equilibrium pressures of hydrogen gases for Li absorbing hydrogen isotopes processes. Results show that all the calculations are feasible. In the reaction of Li absorbing hydrogen gases, the enthalpy and reaction entropy are negative and their absolute values increase with the elevation of temperature, while Gibbs free energy increases toward the positive values. At the same temperature and pressure, the substitutions of
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Key words:
- density function /
- quasi-harmonic debye model /
- thermodynamic functions /
- lih /
- lid /
- lit
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