English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

The non-additive kinetic potential $v^{\text{NAD}}$ is a key quantity indensity-functional theory (DFT) embedding methods, such as frozen densityembedding theory and partition DFT. $v^{\text{NAD}}$ is a bi-functional ofelectron densities $\rho_{\rm B}$ and $\rho_{\rm tot} = \rho_{\rm A} +\rho_{\rm B}$. It can be evaluated using approximate kinetic-energyfunctionals, but accurate approximations are challenging. The behavior of$v^{\text{NAD}}$ in the vicinity of the nuclei has long been questioned, andsingularities were seen in some approximate calculations. In this article, theexistence of singularities in $v^{\text{NAD}}$ is analyzed analytically forvarious choices of $\rho_{\rm B}$ and $\rho_{\rm tot}$, using the nuclear cuspconditions for the density and Kohn-Sham potential. It is shown that nosingularities arise from smoothly partitioned ground-state Kohn-Sham densities.We confirm this result by numerical calculations on diatomic test systems HeHe,HeLi$^+$, and H$_2$, using analytical inversion to obtain a numerically exact$v^{\rm NAD}$ for the local density approximation. We examine features of$v^{\rm NAD}$ which can be used for development and testing of approximationsto $v^{\rm NAD}[\rho_{\rm B},\rho_{\rm tot}]$ and kinetic-energy functionals.

Nuclear cusps and singularities in the non-additive kinetic potential bi-functional from analytical inversion