Linear and nonlinear optical response of crystals using length and velocity gauges: Effect of basis truncation

We study the effects of a truncated band structure on the linear and nonlinear optical response of crystals using four methods. These are constructed by (i) choosing either the length or velocity gauge for the perturbation and (ii) computing the current density either directly or via the time deriva...

Full description

Saved in:
Bibliographic Details
Published in:Physical review. B 2017-11, Vol.96 (19), Article 195413
Main Authors: Taghizadeh, Alireza, Hipolito, F., Pedersen, T. G.
Format: Article
Language:English
Subjects:
Boron nitride
Crystal structure
Gauges
Identification methods
Nonlinear optics
Nonlinear response
Response functions
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:We study the effects of a truncated band structure on the linear and nonlinear optical response of crystals using four methods. These are constructed by (i) choosing either the length or velocity gauge for the perturbation and (ii) computing the current density either directly or via the time derivative of the polarization density. In the infinite-band limit, the results of all four methods are identical, but basis truncation breaks their equivalence. In particular, certain response functions vanish identically and unphysical low-frequency divergences are observed for few-band models in the velocity gauge. Using a hexagonal boron nitride (hBN) monolayer as a case study, we analyze the problems associated with all methods and identify the optimal one. Our results show that the length-gauge calculations provide the fastest convergence rates as well as the most accurate spectra for any basis size and, moreover, that low-frequency divergences are eliminated.
ISSN:2469-9950
2469-9969
DOI:10.1103/PhysRevB.96.195413