We use alchemical first order derivatives for the rapid yet robust prediction of band structures. The power of the approach is demonstrated for the design challenge of finding AlxGa1−xAs semiconductor alloys with large direct band gap using computational alchemy within a genetic algorithm. Dozens of crystal polymorphs are identified for x>32 with direct band gaps larger than 2\:eV according to HSE approximated density functional theory. Based on a single generalized gradient approximated density functional theory band structure calculation of pure GaAs we observe convergence after visiting only ∼800 crystal candidates. The general applicability of alchemical gradients is demonstrated for band structure estimates in III-V and IV-IV crystals as well as for H2 uptake in Sr and Ca-alanate crystals.
@article{arxiv.1805.00299,
title = {Al$_x$Ga$_{1-x}$As crystals with direct 2 eV band gaps from computational alchemy},
author = {K. Y. Samuel Chang and O. Anatole von Lilienfeld},
journal= {arXiv preprint arXiv:1805.00299},
year = {2018}
}