ZrH_2结构与热力学性质

基于密度泛函理论,采用全势线性缀加平面波加局域轨道方法和广义梯度近似研究了ZrH2的结构与弹性性质。结果表明:在基态条件下,ZrH2的晶格常数计算值与实验值及其它理论值相当吻合。在考虑声子作用的前提下,采用准谐德拜模型成功获得了不同条件下(0~50 GPa,0~1 300 K)ZrH2的热容、热膨胀系数和德拜温度等热力学性质。结果表明:定压热容预测值随温度升高而增大,并逐渐接近佩蒂特-杜隆极限;随压强增加,德拜温度呈增加趋势;随温度增加,德拜温度呈减小趋势;在压强一定的条件下,热膨胀系数随温度的升高而增大,且在高温高压条件下,热膨胀系数的增加趋势变缓。

Structure and thermodynamic properties of ZrH2

The structural and elastic properties of ZrH2 are investigated using the full-potential linearized augmented plane wave plus local orbital method within the generalized gradient in the frame of the density functional theory. The ground state properties such as lattice constant, bulk modulus and elastic constants are in good agreement with numerous experimental and theoretical data. Through the quasi-harmonic Debye model, in which the phononic effects are considered, the thermodynamic properties have been obtained successfully, such as thermal expansion coefficient, Debye temperature and heat capacity in the whole pressure range from 0 to 50 GPa and temperature range from 0 to 1 300 K. The results show that heat capacity increases with temperature, tending to the Dulong-Petit limit. Debye t