Efficient lattice dynamics calculations for correlated materials with DFT+DMFT
Efficient lattice dynamics calculations for correlated materials with DFT+DMFT
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DOI：
10.1103/physrevb.102.245104
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发表时间：
2020-08
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影响因子：
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通讯作者：
Can P. Koçer;K. Haule;G. Pascut;B. Monserrat
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文献类型：
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作者：
Can P. Koçer;K. Haule;G. Pascut;B. Monserrat
声子对于许多材料特性至关重要，包括热和电子传输、超导性和结构稳定性。在这里，我们描述了一种使用最先进的 DFT+DMFT 计算来计算相关材料中的声子的方法。我们的方法结合了强大的 DFT+DMFT 实现，通过使用非对角超晶胞的晶格动力学直接方法来计算力。使用非对角超级单元代替对角超级单元大大减少了与 DFT+DMFT 计算相关的计算费用。我们对典型相关材料（Fe、NiO、MnO、SrVO$_3$）的方法进行基准测试，测试 $\mathbf{q}$ 点网格收敛性和 DFT+DMFT 计算的不同计算参数。非对角超胞方法的效率允许我们访问高达 $6\times6\times6$ 的 $\mathbf{q}$ 点网格。此外，我们发现，对于晶格动力学计算中原子所承受的小位移，将自能固定为平衡构型在许多情况下是一个很好的近似，这进一步降低了DFT+DMFT计算的成本。总的来说，我们的工作为使用 DFT+DMFT 计算声子提供了一种有效且通用的方法，为研究相关材料中的晶格动力学和相关现象提供了多种可能性。
Phonons are fundamentally important for many materials properties, including thermal and electronic transport, superconductivity, and structural stability. Here, we describe a method to compute phonons in correlated materials using state-of-the-art DFT+DMFT calculations. Our approach combines a robust DFT+DMFT implementation to calculate forces with the direct method for lattice dynamics using nondiagonal supercells. The use of nondiagonal instead of diagonal supercells drastically reduces the computational expense associated with the DFT+DMFT calculations. We benchmark the method for typical correlated materials (Fe, NiO, MnO, SrVO$_3$), testing for $\mathbf{q}$-point grid convergence and different computational parameters of the DFT+DMFT calculations. The efficiency of the nondiagonal supercell method allows us to access $\mathbf{q}$-point grids of up to $6\times6\times6$. In addition, we discover that for the small displacements that atoms are subject to in the lattice dynamics calculation, fixing the self-energy to that of the equilibrium configuration is in many cases an excellent approximation that further reduces the cost of the DFT+DMFT calculations. Overall, our work provides an efficient and general method for the calculation of phonons using DFT+DMFT, opening many possibilities for the study of lattice dynamics and associated phenomena in correlated materials.