Spin-dependent optimized effective potential formalism for open and closed systems

Article

关键词: DENSITY-FUNCTIONAL THEORY;    METAL SURFACES;    ELECTRON-GAS;    ENERGY;    SEMICONDUCTORS;    APPROXIMATIONS;   

DOI  :  10.1103/PhysRevB.92.235145

来源: SCIE

【 摘 要 】

Orbital-based exchange (x) correlation (c) energy functionals, leading to the optimized effective potential (OEP) formalism of density-functional theory (DFT), are gaining increasing importance in ground-state DFT, as applied to the calculation of the electronic structure of closed systems with a fixed number of particles, such as atoms and molecules. These types of functionals prove also to be extremely valuable for dealing with solid-state systems with reduced dimensionality, such as is the case of electrons trapped at the interface between two different semiconductors, or narrow metallic slabs. In both cases, electrons build a quasi-two-dimensional electron gas, or Q2DEG. We provide here a general DFT-OEP formal scheme valid both for Q2DEGs either isolated (closed) or in contact with a particle bath (open), and show that both possible representations are equivalent, being the choice of one or the other essentially a question of convenience. Based on this equivalence, a calculation scheme is proposed which avoids the noninvertibility problem of the density response function for closed systems. We also consider the case of spontaneously spin-polarized Q2DEGs, and find that far from the region where the Q2DEG is localized, the exact x-only exchange potential approaches two different, spin-dependent asymptotic limits. As an example, aside from these formal results, we also provide numerical results for a spin-polarized jellium slab, using the new OEP formalism for closed systems. The accuracy of the Krieger-Li-Iafrate approximation has been also tested for the same system, and found to be as good as it is for atoms and molecules.

【 授权许可】

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