Lattice dynamics of skutterudites: First-principles and model calculations for CoSb3
Lattice dynamics of skutterudites: First-principles and model calculations for CoSb3
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DOI：
10.1103/physrevb.53.6273
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发表时间：
1996-03-01
影响因子：
3.7
通讯作者：
Singh, DJ
中科院分区：
文献类型：
--
作者：
Feldman, JL;Singh, DJ
用局域密度冻结声子计算方法研究了方钴矿结构CoSb 3的晶格动力学行为，力常数模型与计算结果和实验频率都符合.第一性原理计算的正常模式和频率的伽玛点A（g）的拉曼和A（u）声子，以及受约束的体积模量和它的压力导数。三次非谐项报告的A（g）模式。与现有的键张力常数模型的结果比较发现，最低频率的A（u）声子，其位移模式是由键角调制只有很小的键长变化的协议较差。这种缺乏一致性可能与材料的高度共价键合和模型中没有键角力常数有关。改进的力常数模型，其中包括键角力和再现的第一原理和实验声子频率，开发。声子色散曲线和态密度的报告沿着与弹性常数和德拜温度。
The lattice dynamics of skutterudite structure CoSb3 are investigated by local-density frozen phonon calculations and force-constant model fits to both the results of these calculations and experimental frequencies. First-principles calculations of the normal modes and frequencies are reported for the Gamma-point A(g) Raman and A(u) phonons, as well as the constrained bulk modulus and its pressure derivatives. Cubic anharmonic terms are reported for the A(g) modes. Comparison of the results with an existing bond-stretching force-constant model reveals poor agreement for the lowest frequency A(u) phonon, whose displacement pattern is dominated by bond angle modulation with only small bond length changes. This lack of agreement is probably related to the highly covalent bonding of the material and the absence of bond angle force constants in the model. Improved force-constant models, which include bond angle forces and reproduce both the first-principles and experimental phonon frequencies, were developed. Phonon-dispersion curves and densities of states are reported along with elastic constants and the Debye temperature.