A weight-dependent local correlation density-functional approximation for ensembles

Local approximation of the correlation energy functional in the density matrix functional theory.

A local approximation formula of the correlation energy functional E(c) in terms of the first-order reduced density matrix (1-RDM) is presented. With the contracted Schrödinger equation the principal dependence of E(c) on the natural occupation numbers n(i) is identified. Using the effective mass theory, E(c) is expressed as a functional of the local density and the local variable, J = SUM (i)[...

Bootstrap approximation for the exchange-correlation kernel of time-dependent density-functional theory.

A new parameter-free approximation for the exchange-correlation kernel f(xc) of time-dependent density-functional theory is proposed. This kernel is expressed as an algorithm in which the exact Dyson equation for the response, as well as an approximate expression for f(xc) in terms of the dielectric function, are solved together self-consistently, leading to a simple parameter-free kernel. We a...

Correlation in time-dependent density-functional theory

The exact time-dependent correlation energy in time-dependent density-functional theory is shown to sometimes become positive, which is impossible with most present TDDFT approximations. Both the correlation potential and energy can be strongly nonlocal in time. A new inequality is derived for the time-dependent exchange-correlation energy. The correlation energy appears to scale to a constant ...

Extending the random-phase approximation for electronic correlation energies: the renormalized adiabatic local density approximation

Accounting for spin fluctuations beyond local spin density approximation in the density functional theory

We present a method to correct the magnetic properties of itinerant systems in the local-spin-density approximation (LSDA), and we apply it to the ferromagnetic-paramagnetic transition under pressure in a typical itinerant system Ni3Al. We obtain a scaling of the critical fluctuations as a function of pressure equivalent to the one obtained within Moryia’s theory. Moreover, we show that in this...