Schr\"odinger potentials solvable in terms of the general Heun functions

TL;DR

This paper identifies 11 unique Schr"odinger potentials solvable via general Heun functions, including elementary, elliptic, and hypergeometric sub-potentials, expanding the class of exactly solvable quantum models.

Contribution

It classifies 11 independent potentials with exact solutions in terms of Heun functions, including new elementary and hypergeometric sub-potentials, and explores their integrability properties.

Findings

11 independent potentials with exact solutions in Heun functions

Existence of hypergeometric sub-potentials within these potentials

Presentation of a conditionally integrable generalization of a known solvable potential

Abstract

We show that there exist 35 choices for the coordinate transformation each leading to a potential for which the stationary Schr\"odinger equation is exactly solvable in terms of the general Heun functions. Because of the symmetry of the Heun equation with respect to the transposition of its singularities only eleven of these potentials are independent. Four of these independent potentials are always explicitly written in terms of elementary functions, one potential is given through the Jacobi elliptic sn-function, and the others are in general defined parametrically. Nine of the independent potentials possess exactly or conditionally integrable hypergeometric sub-potentials for which each of the fundamental solutions of the Schr\"odinger equation is written through a single hypergeometric function. Many of the potentials possess sub-potentials for which the general solution is written through fundamental solutions each of which is a linear combination of two or more Gauss hypergeometric functions. We present an example of such a potential which is a conditionally integrable generalization of the third exactly solvable Gauss hypergeometric potential.