Comment on “Electric conductivity in graphene: Kubo model versus a nonlocal quantum field theory model”
Phys. Rev. B 113, 207401 – Published 7 May, 2026
DOI: https://doi.org/10.1103/pvgr-rf1z
Abstract
Recently, P. Rodriguez-Lopez et al., [Phys. Rev. B 111, 115428 (2025)] compared the theoretical descriptions of electric conductivity of graphene given by the Kubo model and quantum field theory in terms of the polarization tensor. According to this article, in the spatially nonlocal case, the quantum field theoretical description contains “hard inconsistencies”. By modifying the equality, which relates the conductivity and polarization expressions, the predictions of quantum field theory were revised and brought in agreement with those following from the nonrelativistic Kubo model. Here, it is shown that this modification violates the requirement of gauge invariance and, thus, is unacceptable. By comparing both theoretical approaches, we demonstrate that all the results obtained within quantum field theory are physically well justified, whereas an application of the modified expression for the conductivity of graphene leads to the consequences of nonphysical character.
