OF-DFT SCF calculations for an H2 molecule using a 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: At., Mol. Opt. Phys., 2018, 51, 055102] that uses the electron distribution n^e(ε) on the energy coordinate ε as a fundamental variable of DFT. The response function χ^e₀ in the integral kernel of the nonlocal functional is also represented on the coordinate ε. As a notable feature in our approach, χ^e₀ of the whole molecule is given by the composite of the response functions of the isolated fragments constituting the molecule. 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.