Comment on "Poynting vector, heating rate, and stored energy in structured materials: A first principles derivation"

TL;DR

This paper critiques Silveirinha's previous work by showing that his excitation model is unphysical, and demonstrates that his formulas are consistent with conventional models when realistic excitation methods are used.

Contribution

The paper clarifies the physical validity of energy and heating rate formulas in structured materials by addressing misconceptions in prior theoretical models.

Findings

Silveirinha's criticism is based on an unphysical excitation model.

Replacing the excitation with realistic external fields aligns Silveirinha's results with previous work.

The misconceptions in Silveirinha's paper are corrected through this analysis.

Abstract

In this Comment I argue that Silveirinha's criticism of my earlier work [M.G.Silveirinha, Phys.Rev.B 80, 235120 2009)] is based on an unphysical excitation model which involves an "external current" which overlaps with a continuous medium but is not subject to constitutive relations. When this excitation model is replaced by the conventional and experimentally-relevant model of excitation by external electromagnetic fields, it can be easily shown that Silveirinha's formulas contain the very results he wanted to disprove. This and a few other misconceptions present in Silveirinha's paper are subject of this Comment.