Constructing a non-additive non-interacting kinetic energy functional approximation for covalent bonds from exact conditions

Kaili Jiang; Jonathan Nafziger; Adam Wasserman

doi:10.1063/1.5051455

Constructing a non-additive non-interacting kinetic energy functional approximation for covalent bonds from exact conditions

J Chem Phys. 2018 Oct 28;149(16):164112. doi: 10.1063/1.5051455.

Authors

Kaili Jiang¹, Jonathan Nafziger², Adam Wasserman¹

Affiliations

¹ Department of Physics and Astronomy, Purdue University, 525 Northwestern Ave., West Lafayette, Indiana 47907, USA.
² Department of Chemistry, Purdue University, 560 Oval Dr., West Lafayette Indiana 47907, USA.

PMID: 30384751
DOI: 10.1063/1.5051455

Abstract

We present a non-decomposable approximation for the non-additive non-interacting kinetic energy (NAKE) for covalent bonds based on the exact behavior of the von Weizsäcker (vW) functional in regions dominated by one orbital. This covalent approximation (CA) seamlessly combines the vW and the Thomas-Fermi functional with a switching function of the fragment densities constructed to satisfy exact constraints. It also makes use of ensembles and fractionally occupied spin-orbitals to yield highly accurate NAKE for stretched bonds while outperforming other standard NAKE approximations near equilibrium bond lengths. We tested the CA within Partition-Density Functional Theory (P-DFT) and demonstrated its potential to enable fast and accurate P-DFT calculations.