Is it possible to construct excited-state energy functionals by splitting k-space?

TL;DR

This paper demonstrates that constructing excited-state energy functionals through k-space splitting is a versatile approach, successfully extending to kinetic energy functionals with comparable accuracy to ground-state functionals.

Contribution

It introduces a general method for creating excited-state energy functionals by splitting k-space, applicable beyond exchange energies to kinetic energy functionals.

Findings

The method yields excited-state kinetic energy functionals with accuracy comparable to ground-state functionals.

The approach is validated by constructing a modified Thomas-Fermi kinetic energy functional and its gradient expansion.

The technique is shown to be broadly applicable for excited-state energy functional development.

Abstract

We show that our procedure of constructing excited-state energy functionals by splitting k-space, employed so far to obtain exchange energies of excited-states, is quite general. We do so by applying the same method to construct modified Thomas-Fermi kinetic energy functional and its gradient expansion up to the second order for the excited-states. We show that the resulting kinetic energy functional has the same accuracy for the excited-states as the ground-state functionals do for the ground-states.