Pair density functional theory by means of the correlated wave function

TL;DR

This paper introduces a new density functional approach for calculating pair densities using correlated wave functions, overcoming previous limitations related to N-representability and kinetic energy functionals.

Contribution

It presents a novel scheme that extends the search space for ground-state pair densities beyond earlier theories, including Hartree-Fock.

Findings

Extended the variational search region for pair densities

Achieved more accurate pair density calculations beyond Hartree-Fock

Provided a practical scheme free from N-representability constraints

Abstract

We present a density functional scheme for calculating the pair density (PD) by means of the correlated wave function. This scheme is free from both of problems related to PD functional theory, i.e., (a) the need to constrain the variational principle to $N$-representable PDs and (b) the development of a kinetic energy functional. By using the correlated wave function, the searching region for the ground-state PD is substantially extended as compared with our previous theory[Physica B \textbf{372} (2007), in press]. The variational principle results in the simultaneous equations that yield the best PD beyond the previous theory, not to mention the Hartree-Fock approximation.