基于自洽GW方法的碳化硅准粒子能带结构计算

Quasiparticle band structure calculation for SiC using self-consistent GW method

在多体微扰理论的框架下,分别采用G_0W_0方法和准粒子自洽GW方法计算3C-SiC和2H-SiC的准粒子能级.由一个平均Monkhorst-Pack网格点上的准粒子能级和准粒子波函数出发,结合最局域Wannier函数插值,得到3C-SiC和2H-SiC的自洽准粒子能带结构.3C-SiC的价带顶在Γ点,导带底在X点.DFT-LDA,G_0W_0和准粒子自洽GW给出的3C-SiC间接禁带宽度分别为1.30eV,2.23 eV和2.88eV 2H-SiC价带顶在Γ点,导带底在K点.采用DFT-LDA,G_0W_0和准粒子自洽GW方法得到的间接禁带宽度分别为2.12 eV,3.12 eV和3.75 eV.计算基于赝势方法,对于3C-SiC和2H-SiC的准粒子自洽GW计算给出的禁带宽度均比实验值略大.

Quasiparticle band structures of 3C-SiC and 2H-SiC were calculated using ab initio many body perturbation theory with GW approximation. Quasiparticle energies along high symmetry lines in the first Brillouin zone were evaluated using quasiparitcle selfconsistent GW （QPscGW） method and the Maximally-localized Wannier Function interpolation. Both 3C-SiC and 2H-SiC have an indirect band gap with valence band maximum locating at F point. The conduction band maximum of 3C-SiC is at X point. As a comparison, band gaps of 3C-SiC calculated by DFT-LDA, one-shot GoW0 and QPscGW are 1.30 eV, 2.23 eV and 2.88 eV respectively. The conduction band minimum of 2H-SiC locates at K point with a band gap of 2.12 eV, 3.12 eV and 3.75 eV predicted by DFTLDA, one-shot GoW0 and QPscGW respectively. Lattice parameters calculated by DFT-LDA were used in this work. The QPscGW calculations are based on pseudopotential method, predicting slightly larger bandgaps for both 3C-SiC and 2H-SiC comparing with experiments.