Comment on "Response calculations with an independent particle system with an exact one-particle density matrix''

TL;DR

This paper critiques a previous claim by identifying an error in the argument that links phase invariance of natural orbitals to the time independence of occupation numbers in the adiabatic approximation.

Contribution

It clarifies the incorrect assumption in prior work regarding the invariance of the interaction energy functional and its implications for occupation number dynamics.

Findings

Identifies an error in the previous argument about phase invariance.

Shows that occupation numbers can vary despite phase invariance.

Clarifies the relationship between energy functionals and orbital phases.

Abstract

We point out an error in the argument [PRL 105, 013002 (2010)] that the time independence of the occupation numbers in the adiabatic approximation follows from the invariance of the ground-state interaction energy functional with respect to changes in the phases of the natural orbitals.