An exactly soluble Schrodinger equation with smooth position-dependent mass

The one-dimensional generalized Schrodinger equation for a system with smooth potential and mass step is resolved exactly. The wave function depends on the Heun's function, which is a solution of a second-order Fuchsian equation with four singularities. The behavior of the transmission coefficient as a function of energy is compared to that of the case of an abrupt potential and mass step. Two limiting cases are also studied: when the width of the mass step is vanishing, and when the smooth potential and mass step tend to an abrupt potential and mass step. (C) 1998 American Institute of Physics.