Comment on "Density and Physical Current Density Functional Theory" by Xiao-Yin Pan and Viraht Sahni, Int. J. Quant. Chem. 110, 2833 (2010)

TL;DR

This paper critiques a previous formulation of physical current density functional theory, arguing it is a flawed reformulation that complicates the variational principle and the construction of the universal functional.

Contribution

It clarifies that the criticized formulation is a misrepresentation of established current-density functional theory, highlighting potential errors and conceptual issues.

Findings

The formulation is a garbled reformulation of Vignale-Rasolt theory.

It complicates the variational principle.

It hampers the construction of the universal functional.

Abstract

This comment criticizes the above paper by Xiao-Yin Pan and Viraht Sahni. It is shown that their formulation of "Physical Current Density Functional Theory" is, at best, a garbled reformulation of the Vignale-Rasolt current-density functional theory, and, at worst, a potential source of mistakes insofar as it complicates the formulation of the variational principle and prevents the constrained search construction of the universal functional.