氟化锂晶体热输运性质的理论研究

摘要

基于第一性原理理论求解玻尔兹曼运输方程的迭代解方法准确计算了氟化锂的晶格热导率.采用实空间有限差分超晶胞方法来计算二阶力常数和三阶的力常数.然后通过二阶力常数和三阶原子力常数计算氟化锂晶体的相关物理性质.结果表明,室温下氟化锂的晶格热导率为13.89 W/(m·K),与实验结果一致,这表明这种计算方法可以准确得到这种材料的晶格热导率.%The lattice thermal conductivity of lithium fluoride(LiF)is accurately computed from a first-principles theoretical approach based on an iterative solution of the Boltzmann transport equation.Real-space finite-difference supercell approach is employed to generate the second-and third-order interatomic force constants.Then the related physical quantities of LiF crystal are calculated by the second-and third-order potential interactions at 30 to 1000 K.The calculated lattice thermal conductivity 13.89 W/(m·K)for LiF at room temperature agrees well with the experimental value,demonstrating that the approach can furnish precise descriptions of the lattice thermal conductivity of this material.