Recent Development of the Pair Density Functional Theory

The pair density (PD) functional theory is one of the promising theories to go beyond the conventional density functional theory. The main feature of the PD functional theory is that the PD functional theory in principle can reproduce the ground-state PD that essentially contains more information on the electron–electron interaction than the electron density. In order to develop the PD functional theory, it is indispensable to devise the approximate form of the kinetic energy (KE) as a functional of the PD. In this paper, we review our recent approaches about how to develop the approximate KE functional, and show the latest results of the atomic structure calculations for the closed shell atoms.