Lattice dynamics and electron-phonon coupling calculations using nondiagonal supercells
Lattice dynamics and electron-phonon coupling calculations using nondiagonal supercells
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DOI：
10.1103/physrevb.92.184301
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发表时间：
2015-11-06
影响因子：
3.7
通讯作者：
Monserrat, Bartomeu
中科院分区：
文献类型：
--
作者：
Lloyd-Williams, Jonathan H.;Monserrat, Bartomeu
我们研究使用具有非零非对角元素的超晶胞矩阵直接计算晶格动力学和电子声子耦合计算的总能量导数。我们证明，可以使用包含等于 n(1)、n(2) 和 n(3) 最小公倍数的原始单元数量的超单元来确定周期系统对以具有简化分数坐标 (m(1)/n(1)、m(2)/n(2)、m(3)/n(3)) 的波矢量为特征的扰动的响应。如果仅使用对角超胞矩阵，则需要包含 n(1)n(2)n(3) 个本原胞的超胞。我们证明，使用非对角超晶胞可以显着降低获得金刚石和石墨的收敛零点能量和声子色散的计算成本。我们还使用直接方法进行电子声子耦合计算，以前所未有的尺寸网格对振动布里渊区进行采样，这使我们能够研究零点重整化对金刚石热和光学带隙的收敛性。
We study the direct calculation of total energy derivatives for lattice dynamics and electron-phonon coupling calculations using supercell matrices with nonzero off-diagonal elements. We show that it is possible to determine the response of a periodic system to a perturbation characterized by a wave vector with reduced fractional coordinates (m(1)/n(1), m(2)/n(2), m(3)/n(3)) using a supercell containing a number of primitive cells equal to the least common multiple of n(1), n(2), and n(3). If only diagonal supercell matrices are used, a supercell containing n(1)n(2)n(3) primitive cells is required. We demonstrate that the use of nondiagonal supercells significantly reduces the computational cost of obtaining converged zero-point energies and phonon dispersions for diamond and graphite. We also perform electron-phonon coupling calculations using the direct method to sample the vibrational Brillouin zone with grids of unprecedented size, which enables us to investigate the convergence of the zero-point renormalization to the thermal and optical band gaps of diamond.