Constraint-based wave vector and frequency dependent exchange-correlation kernel of the uniform electron gas

Article

关键词: DENSITY-FUNCTIONAL THEORY;    LOCAL-FIELD FACTOR;    CORRELATION ENERGIES;    EXCITATION-ENERGIES;    GROUND-STATE;    ACCURATE;   

DOI  :  10.1103/PhysRevB.101.245135

来源: SCIE

【 摘 要 】

According to time-dependent density functional theory, the exact exchange-correlation kernel f(xc)(n, q, omega) for wave vector q and frequency omega determines not only the ground-state energy but also the excited-state energies/lifetimes and time-dependent linear density response of an electron gas of uniform density n = 3/(4 pi r(s)(3)). Here we propose a parametrization of this function based upon the satisfaction of exact constraints. For the static (omega = 0) limit, we modify the model of Constantin and Pitarke to recover at small q the known second-order gradient expansion, and to correct its approach to the large q limit. For all omega at q = 0, we use the model of Gross, Kohn, and Iwamoto. A Cauchy integral extends this model to complex N. Scaling relations are identified. We then combine these ingredients, damping out the omega dependence at large q. Away from q = 0 and omega = 0, the correlation contribution to the kernel becomes dominant over exchange, even at r(s) = 4. The resulting correlation energies for 1 <= r(s) <= 10 from integration over imaginary omega are essentially exact. The plasmon pole of the density response function is found by analytic continuation of f(xc) to omega just below the real axis, and the resulting plasmon lifetime at r(s) = 4 is found for q < k(F). A static charge-density wave is found for r(s) > 69, and shown to be associated with softening of the plasmon mode.

【 授权许可】

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