Assessing the role of interatomic position matrix elements in tight-binding calculations of optical properties
Julen Ibañez-Azpiroz, Fernando de Juan, Ivo Souza
SciPost Phys. 12, 070 (2022) · published 22 February 2022
- doi: 10.21468/SciPostPhys.12.2.070
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Abstract
We study the role of hopping matrix elements of the position operator $\mathbf{\hat{r}}$ in tight-binding calculations of linear and nonlinear optical properties of solids. Our analysis relies on a Wannier-interpolation scheme based on \textit{ab initio} calculations, which automatically includes matrix elements of $\mathbf{\hat{r}}$ between different Wannier orbitals. A common approximation, both in empirical tight-binding and in Wannier-interpolation calculations, is to discard those matrix elements, in which case the optical response only depends on the on-site energies, Hamiltonian hoppings, and orbital centers. We find that interatomic $\mathbf{\hat{r}}$-hopping terms make a sizeable contribution to the shift photocurrent in monolayer BC$_2$N, a covalent acentric crystal. If a minimal basis of $p_z$ orbitals on the carbon atoms is used to model the band-edge response, even the dielectric function becomes strongly dependent on those terms.
Cited by 2

Authors / Affiliations: mappings to Contributors and Organizations
See all Organizations.- 1 2 Julen Ibanez,
- 2 3 Fernando de Juan,
- 1 2 Ivo Souza
- 1 Euskal Herriko Unibertsitatea / University of the Basque Country [UPV]
- 2 Basque Foundation for Science / Ikerbasque
- 3 Donostia International Physics Center [DIPC]
- European Research Council [ERC]
- Horizon 2020 (through Organization: European Commission [EC])
- Ministerio de Economía y Competitividad (MINECO) (through Organization: Ministerio de Economía, Industria y Competitividad / Ministry of Economy, Industry and Competitiveness [MINECO])