2025/12/12 by Huaman, Angiolo, Rosas-Hernandez, Luis Enrique, Barraza-Lopez, Salvador
#FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci)
paper · doi:10.48550/arxiv.2512.12079
The second-order optical susceptibility of semiconductors χijk(2)(-2ω;ω,ω) finds application in metrology, spectroscopy, telecommunications, material characterization, and quantum information. Pioneering calculations of χijk(2)(-2ω;ω,ω) utilized non-orthogonal Gaussian orbitals centered at atoms. That formulation transitioned into plane-wave-based algorithms as time went by. As of late, nevertheless, multiple tools for calculating optical susceptibilities have recast the problem using Wannier (\em i.e., \em localized) orbitals, making a comeback onto frameworks based on localized basis sets. Here, we present an approach for calculating χijk(2)(-2ω;ω,ω) reliant on numerical pseudoatomic orbitals (PAOs) within perturbation theory in the velocity gauge. Its salient feature is a calculation of `Slater-Koster-like' two-center integrals of the momentum operator in between PAOs identified by symmetry. The approach was successfully tested on paradigmatic cubic silicon carbide (3C-SiC) and gallium arsenide, for which linear responses are contributed as well.