MgS和MgSe带隙的GW近似修正
Band gap correction of MgS and MgSe in GW approximation

应用基于密度泛函理论下的局域密度近似（DFT-LDA）方法研究了岩石矿结构的 MgS和MgSe的晶体结构和能带结构。本文得到稳定结构的晶格常数与已知实验数据相吻合，MgS和MgSe都是间接带隙半导体且带隙值分别为2.74 eV和1.70 eV。尽管本文利用LDA计算的带隙值与之前的理论值很接近，但是局域密度近似常常低估带隙值。因此应用准粒子GW（G是格林函数，W是库伦屏蔽相互作用）近似 对MgS和MgSe的带隙值进行了修正，其结果分别为4.15eV和2.74 eV。GW近似的结果应该是合适的值。
The structural, electronic properties of MgS and MgSe in rocksalt were calculation using local density approximation in density-functional theory（DFT-LDA）. The calculated lattice parameters are in excellent agreement with the experiment values. The results by using LDA show that both MgS and MgSe are indirect band gap materials and the band gaps are 2.74 eV and 1.70 eV for MgS and MgSe, respectively. Though these band gaps are consistent with previous theoretical values, LDA calculations usually underestimate the band gap values. It is necessary to employ the GW (G is Green’s function and W is the screened Coulomb interaction) approximation to correct the band gap values. The obtained results are 4.15 eV and 2.74 eV for MgS and MgSe in rocksalt by using GW approximation respectively. It is expected that GW approximation should be very appropriate。