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含有开壳层4f局域电子的稀土材料体系,因其独特的物理化学性质而在基础和应用研究领域受到广泛关注。从第一性原理理论计算的角度,通常的局域密度近似或广义梯度近似下的密度泛函理论(DFT)方法,因为对局域f-电子的描述存在严重的自相互作用误差,难以正确描述这一类强关联体系的基态性质。被广泛地应用于强关联材料的第一性原理计算的DFT+U方法,通常需要人为指定屏蔽库伦作用参数,削弱了它对新体系的预测能力。本工作中,我们在密度泛函理论的框架下,采用Thomas-Fermi模型,发展了一种体系自洽的局域屏蔽库伦修正方法,该方法基于局域空间内的电子密度自洽地获得体系依赖的屏蔽作用参数。将该方法应用于研究Eu X(X=O,S,Se,Te)体系的电子能带结构和磁性质,取得了较为合理的结果,验证了方法的有效性。
Rare earth material systems containing open-shell 4f local electrons have received widespread attention in basic and applied research due to their unique physico-chemical properties. From the perspective of theoretical calculations of first principles, the density functional theory (DFT) method, which is usually approximated by local density or generalized gradient approximation, has serious self-interaction errors in the description of local f-electrons and is difficult to correct Describe the ground state properties of this type of strongly related system. The DFT + U method, which is widely used in first-principles calculations of strongly related materials, usually requires artificially specifying the parameters that shield the Coulomb action and weakening its ability to predict new systems. In this work, we developed a self-consistent local shielding Coulomb correction method using the Thomas-Fermi model in the framework of density functional theory. This method obtains the system based on the electron density in local space Dependent masking effect parameters. The proposed method is applied to study the electronic band structure and magnetic properties of Eu X (X = O, S, Se, Te) system. The reasonable results are obtained and the validity of the method is verified.