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arXiv 2103.05409cond-mat.mtrl-sci
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投影增强波法中的动态横向磁化率。应用于Fe、Ni和Co

Dynamic transverse magnetic susceptibility in the projector augmented-wave method. Application to Fe, Ni, and Co

Thorbjørn Skovhus, Thomas Olsen

摘要:

我们提出了一个第一性原理实现的动态横向磁化率的线性响应依赖于时间的密度泛函理论的框架。动态磁化率允许一个获得的磁振子色散以及磁振子寿命为特定的材料,这极大地促进了非弹性中子散射实验以及其他光谱技术的解释。我们将该方法应用于Fe,Ni和Co,并在基组大小,$k$点采样,光谱拖尾和未占用频带方面进行了彻底的收敛性分析。特别是,它示出,而间隙误差(声磁振子能量在$\mathbf{q}=\mathbf{0}$)是非常具有挑战性的收敛,自旋波刚度和色散关系本身是收敛参数的敏感性低得多。我们的最终结果与实验提取的磁振子色散关系,除了镍,这是众所周知的,交换分裂能量是很差的局部密度近似表示。我们还发现与以前的第一性原理计算很好的协议,并解释如何在计算的色散关系的差异,可以产生计算方法的细微差异。

英文摘要:

We present a first principles implementation of the dynamic transverse magnetic susceptibility in the framework of linear response time-dependent density functional theory. The dynamic susceptibility allows one to obtain the magnon dispersion as well as magnon lifetimes for a particular material, which strongly facilitates the interpretation of inelastic neutron scattering experiments as well as other spectroscopic techniques. We apply the method to Fe, Ni, and Co and perform a thorough convergence analysis with respect the basis set size, $k$-point sampling, spectral smearing and unoccupied bands. In particular, it is shown that while the gap error (acoustic magnon energy at $\mathbf{q}=\mathbf{0}$) is highly challenging to converge, the spin-wave stiffness and the dispersion relation itself are much less sensitive to convergence parameters. Our final results agrees well with experimentally extracted magnon dispersion relations except for Ni, where it is well-known that the exchange splitting energy is poorly represented in the local density approximation. We also find good agreement with previous first principles calculations and explain how differences in the calculated dispersion relations can arise from subtle differences in computational approaches.

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