Non-additive Non-interacting Kinetic Energy of Rare Gas Dimers

Abstract

Approximations of the non-additive non-interacting kinetic energy (NAKE) as an explicit functional of the density are the basis of several electronic structure methods that provide improved computational efficiency over standard Kohn-Sham calculations. However, within most fragment-based formalisms, there is no unique exact NAKE, making it difficult to develop general, robust approximations for it. When adjustments are made to the embedding formalisms to guarantee uniqueness, approximate functionals may be more meaningfully compared to the exact unique NAKE. We use numerically accurate inversions to study the exact NAKE of several rare-gas dimers within Partition Density Functional Theory, a method that provides the uniqueness for the exact NAKE. We find that the NAKE decreases nearly exponentially with atomic separation for the rare gas dimers. We compute the logarithmic derivative of the NAKE with respect to the bond length for our numerically accurate inversions as well as for several approximate NAKE functionals. We show that standard approximate NAKE functionals do not reproduce the correct behavior for this logarithmic derivative, and propose two new NAKE functionals that do. The first of these is based on a re-parametrization of a conjoint PBE functional. The second is a simple, physically-motivated non-decomposable NAKE functional that matches the asymptotic decay constant without fitting.

References in corpus (5)

• Nonlocal van der Waals density functional: The simpler the better
• Libxc: a library of exchange and correlation functionals for density functional theory
• The Importance of being consistent
• Numerical Methods for the Inverse Problem of Density Functional Theory
• Nonlocal Kinetic Energy Functionals By Functional Integration

Cited by in corpus (4)

• Orbital-free approximations to the kinetic-energy density in exchange-correlation MGGA functionals: tests on solids
• Constructing a Non-additive Non-interacting Kinetic Energy Functional Approximation for Covalent Bonds from Exact Conditions
• Exact partition potential for model systems of interacting electrons in 1-D
• Stretching bonds in Density Functional Theory without artificial symmetry breaking