Comment on "Ab initio calculation of the shift photocurrent by Wannier interpolation"

TL;DR

This paper discusses the necessity of adding a correction term when using a finite broadening parameter in Wannier interpolation to ensure phase convention independence in calculating the generalized derivative of the interband dipole matrix.

Contribution

It highlights the importance of a correction term in the formula to account for finite broadening effects, improving the accuracy of Wannier-based calculations.

Findings

Correction term is necessary for phase independence with finite broadening.

The original formula requires modification for practical calculations.

Ensures more reliable and consistent results in shift photocurrent calculations.

Abstract

In a recent paper, Iba\~nez-Azpiroz et al. [Phys. Rev. B 97, 245143 (2018)] derive a band-truncation-error-free formula for calculating the generalized derivative of the interband dipole matrix using Wannier interpolation. In practice, the denominators involving intermediate states are regularized by introducing a finite broadening parameter. In this Comment, I show that when a finite broadening parameter is used, a correction term must be added to the generalized derivative to obtain results that are independent of the phase convention for the Bloch sums.