Schrödinger Equation for a One-Dimensional Delta Function Potential

After the free particle, the most elementary example of a one-dimensional time-independent Schrödinger equation is conceptually that of a particle in a delta function potential: (in units with ). For an attractive potential, with , there is exactly one bound state, with and . Note that and . Since the delta function has dimensions of , this solution is considered the one-dimensional analog of a hydrogen-like atom. The bound state, in fact, resembles a cross section of a 1 orbital .

For , free particles are scattered by a delta function potential. The positive-energy solutions can be written , with . The amplitudes of the transmitted and reflected waves are accordingly given by and , respectively. Note that these are the same for attractive and repulsive delta funtion potentials, independent of the sign of .

For continuum states, the graphic shows a wave incident from the left. The transmitted wave is shown on the right in blue and the reflected wave, on the left in red, with opacities indicating relative wave amplitudes.