Department of Physics, University of Tokyo, Tokyo 113-0033, Japan.
Laboratory for Materials and Structures, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama 226-8503, Japan.
J Chem Phys. 2019 Mar 21;150(11):114104. doi: 10.1063/1.5079474.
We propose two schemes for interpolation of the one-particle Green's function (GF) calculated within a coupled-cluster singles and doubles (CCSD) method for a periodic system. These schemes use Wannier orbitals for circumventing huge cost for a large number of sampled k points. One of the schemes is the direct interpolation, which obtains the GF straightforwardly by using Fourier transformation. The other is the self-energy-mediated interpolation, which obtains the GF via the Dyson equation. We apply the schemes to a LiH chain and trans-polyacetylene and examine their validity in detail. It is demonstrated that the direct-interpolated GFs suffer from numerical artifacts stemming from slow convergence of CCSD GFs in real space, while the self-energy-mediated interpolation provides more physically appropriate GFs due to the localized nature of CCSD self-energies. Our schemes are also applicable to other correlated methods capable of providing GFs.
我们提出了两种方案，用于对周期性系统中单粒子格林函数（GF）进行插值，该 GF 是通过耦合簇单双激发（CCSD）方法计算得到的。这些方案使用了 Wannier 轨道，以避免在大量采样的 k 点上花费大量成本。其中一种方案是直接插值，它通过傅里叶变换直接获得 GF。另一种是自能介导插值，它通过 Dyson 方程获得 GF。我们将这些方案应用于 LiH 链和反式聚乙炔，并详细检查了它们的有效性。结果表明，直接插值 GF 受到了 CCSD GF 在实空间中收敛缓慢所导致的数值伪影的影响，而自能介导插值由于 CCSD 自能的局域性质，提供了更符合物理实际的 GF。我们的方案也适用于其他能够提供 GF 的相关方法。
