In an exercise in quantum mechanics an elementary change of
variables is used to map the well known Morse-potential model
(possessing Laguerre-polynomial eigenfunctions) onto an equivalent
Schroedinger-like differential bound-state problem where the
``effective" mass is allowed coordinate-dependent.

MR2402972 Tezcan, Cevdet; Sever, Ramazan; Ye\c silta\c s, Özlem A
new approach to the exact solutions of the effective mass
Schrödinger equation. Internat. J. Theoret. Phys. 47 (2008), no.
6, 1713--1721. 81Q05