OF-DFT SCF calculations for H2 molecule using nonlocal kinetic energy functional defined on energy coordinate

Abstract

A nonlocal kinetic energy density functional in the orbital-free density functional theory(OF-DFT) is utilized to perform the SCF calculations for an H₂ molecule. The functional is formulated within the framework of the novel DFT [Takahashi, J. Phys. B, 2018, 51, 055102] that uses the electron distribution n^e(ε) on the energy coordinate ε as a fundamental variable of the DFT. The coordinate ε is defined as the interaction potential between an electron and nuclei in the molecule under consideration. Accordingly, the response function χ₀^e in the integral kernel of the nonlocal functional is represented on the coordinate ε. As a notable feature in our approach, χ₀^e of the whole molecule is given by the composite of the response functions of the isolated fragments constituting the molecule. The property of the composite response function is investigated. The electron density and the potential energy curve of the H₂ molecule are computed by the OF-DFT SCF calculations, showing reasonable agreements with those obtained by the Kohn-Sham DFT calculations.