Exact solution of the Schrödinger equation for a hydrogen atom at the interface between the vacuum and a topologically insulating surfaceDaniel A. Bonilla, Alberto Martín-Ruiz and Luis F. UrrutiaEur. Phys. J. D, 73 6 (2019) 114DOI: https://doi.org/10.1140/epjd/e2019-90347-2