First-principles comparison of PBE,PBE+U and HSE predictions for bulk phase properties of Fe₃O₄ and Fe₅C₂

【作者】 孟宇； 温晓东； 曹东波； 杨勇； 李永旺；

【机构】 中国科学院山西煤炭化学研究所；

【摘要】 Classical LSDA predicts wrong results about gap for the Mott-Hubbard insulator and charge ordering systems such as Fe3O4,LDA+U and HSE methods are proved to be quite successful in correcting LDA approximation for treating with strong electron-electron correlations.This work concentrates on a systematic comparison of the lattice structures,electronic and optical properties of Fe3O4 and Fe5C2,predicted by density functional theory using PBE,PBE+U and the Heyd-Scuseria-Ernzerhof screened hybrid density functional(HSE).For Fe3O4,they give a consistent ferrimagnetism ground state.PBE+U(U≈4e V)and HSE(μ≈0.207)can produce a good description about structure parameters,magnetic,electronic structure and optical properties.With regard to HSE method,increasing screened constantμhas a little effect on lattice parameters but leads to decreasing Fe magnetic moment and decreasing d-electrons coulomb repulsion.All results obtained using large screened constantμare close to that in the case of PBE functional.For Fe5C2,ferromagnetism ground state is exactly predicted by three approximations.PBE is a suite approximation predicting about structure parameters,magnetic,electronic structure and optical properties.For HSE,Fe5C2 show the rule analogous to Fe3O4 withμincreasing.A significant conclusion is that we should adopt reasonable screening constantμcombining with the nature of system to accurately predict the material properties by HSE functional.更多还原

【Abstract】 Classical LSDA predicts wrong results about gap for the Mott-Hubbard insulator and charge ordering systems such as Fe3O4,LDA+U and HSE methods are proved to be quite successful in correcting LDA approximation for treating with strong electron-electron correlations.This work concentrates on a systematic comparison of the lattice structures,electronic and optical properties of Fe3O4 and Fe5C2,predicted by density functional theory using PBE,PBE+U and the Heyd-Scuseria-Ernzerhof screened hybrid density functional(HSE).For Fe3O4,they give a consistent ferrimagnetism ground state.PBE+U(U≈4e V)and HSE(μ≈0.207)can produce a good description about structure parameters,magnetic,electronic structure and optical properties.With regard to HSE method,increasing screened constantμhas a little effect on lattice parameters but leads to decreasing Fe magnetic moment and decreasing d-electrons coulomb repulsion.All results obtained using large screened constantμare close to that in the case of PBE functional.For Fe5C2,ferromagnetism ground state is exactly predicted by three approximations.PBE is a suite approximation predicting about structure parameters,magnetic,electronic structure and optical properties.For HSE,Fe5C2 show the rule analogous to Fe3O4 withμincreasing.A significant conclusion is that we should adopt reasonable screening constantμcombining with the nature of system to accurately predict the material properties by HSE functional.更多还原