paper

Efficient many-body calculations of 2D materials using exact limits for the screened potential: Band gaps of MoS, hBN, and phosphorene

arXiv:1511.00129 · doi:10.1103/PhysRevB.94.155406

Abstract

Calculating the quasiparticle (QP) band structure of two-dimensional (2D) materials within the GW self-energy approximation has proven to be a rather demanding computational task. The main reason is the strong -dependence of the 2D dielectric function around that calls for a much denser sampling of the Brillouin zone than is necessary for similar 3D solids. Here we use an analytical expression for the small -limit of the 2D response function to perform the BZ integral over the critical region around . This drastically reduces the requirements on the -point mesh and implies a significant computational speed-up. For example, in the case of monolayer MoS, convergence of the band gap to within is achieved with -points rather than the mesh required with discrete BZ sampling techniques. We perform a critical assessment of the band gap of the three prototypical 2D semiconductors MoS, hBN, and phosphorene including the effect of self-consistency at the GW and GW level. The method is implemented in the open source GPAW code.

9 pages, 4 figures

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