First-principles study of the structural, electronic, vibrational, and elastic properties of orthorhombic NiSi
First-principles study of the structural, electronic, vibrational, and elastic properties of orthorhombic NiSi
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DOI：
10.1103/physrevb.79.094101
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发表时间：
2009-03-01
影响因子：
3.7
通讯作者：
Thomas, O.
中科院分区：
文献类型：
--
作者：
Connetable, D.;Thomas, O.
我们利用密度泛函理论和密度泛函微扰理论，利用交换相关泛函的Perdew-Burke-Ernzerhof广义梯度近似，在其自旋极化版本中，对正交NiSi结构的结构、电子、振动和弹性性质进行了研究。优化后的晶格参数、形成能和振动性能与实验数据基本一致。我们证明了NiSi不是铁磁性的，在费米能级上具有低密度的态。用三种不同的方法计算了弹性常数，以供比较。在前两种方法中，计算出的能量E作为变形的函数拟合，原子位置在模拟过程中要么松弛，要么不松弛。原子弛豫可以显著地改变弹性常数。在第三种方法中，我们把声速和弹性常数联系起来。NiSi具有高度的各向异性。特别是沿b轴的线性体积模量比沿其他轴的大得多。多晶弹性性能和德拜温度也进行了评估，以完整地描述弹性性能。
We present a study of the structural, electronic, vibrational, and elastic properties of the orthorhombic NiSi structure by means of the density-functional theory and the density-functional perturbative theory, with the Perdew-Burke-Ernzerhof generalized gradient approximation of the exchange-correlation functional, within its spin-polarized version. The optimized lattice parameters, the formation energy, and vibrational properties are found in agreement with experimental data. We show that NiSi is not ferromagnetic, with a low density of states at the Fermi level. Elastic constants have been calculated by means of three different approaches for comparison. In the first two, the calculated energy E is fitted as a function of the deformation, atomic positions are either relaxed or not relaxed during the simulations. Atomic relaxations are shown to modify significantly elastic constants. In the third approach we have related acoustic velocities to elastic constants. NiSi is shown to be highly anisotropic. In particular the linear bulk modulus along b axis is much larger than along other axes. Polycrystalline elastic properties and Debye temperature have been also evaluated for a complete description of elastic properties.