Reconsidering Power Functional Theory

TL;DR

This paper revisits and simplifies the derivation of Power Functional Theory, clarifying its foundations and proposing modifications that relate it more closely to classical Density Functional Theory.

Contribution

It provides a clearer, more explicit derivation of Power Functional Theory and introduces modifications to address issues in the original formulation.

Findings

Simplified the derivation of Power Functional Theory

Proposed a modification to improve the theory's consistency

Established a surprising connection to classical Density Functional Theory

Abstract

The original derivation of Power Functional Theory, Schmidt and Brader, JCP 138, 214101 (2013), is reworked in some detail with a view to clarifying and simplifying the logic and making explicit the various functional dependencies. We note various issues with the original development and suggest a modification that allows us to avoid them. In the process we also suggest an alternative interpretation of our results that bears surprising similarities to classical Density Functional Theory.