利用第一性原理平面波赝势密度泛函理论,并结合准谐德拜模型,计算了立方萤石结构ErH2在不同温度和压强下的体积、热膨胀系数、体弹模量和等体热容等弹性性质及热力学性质.在温度高于1100K的条件下,计算出的等体热容趋近于Dulong-Petit极限.得到了绝对零度、零压强下ErH2的该结构的晶格常数为0.5232 nm,与实验值0.5230 nm非常接近.由不同的原胞体积得出了该体系的单点能与原胞体积的关系的数据；从计算出的高压下的弹性常数,根据立方晶系的力学稳定性条件,推断出立方萤石结构ErH2的相变压力约为20 GPa.%First principles theoretical study of the elastic and thermodynamic properties of erbium dihydride in fluorite structure, such as volume, thermal expansion, bulk modulus and isochoric heat capacity at different temperatures and pressures is performed using the plane wave pseudopotential method and the quasi-harmonic Deb ye model. The calculated isochoric heat capacity is convergent to the Dulong-Pctit limit at temperatures over 1 100 K. The calculated lattice parameter of 0. 523 2 nm at 0 GPa, and 0 K is in excellent agreement with the experimental value of 0. 523 0 nm. Simultaneously, the data of single point energy versus volume of primitive cell are also calculated. According to the calculated values of the elastic constants at high pressures and the mechanical stability criteria of cubic crystals, the phase transition pressure is inferred to be about 20 GPa, which is a valid theoretical reference value for further experimental work in high pressure research.
展开▼
