Solve Schroedinger Equation with Mathematica DSolve for given potential

[donquixote17]

Homework Statement

I need to solve the Schroedinger equation (Using DSolve in Mathematica) for a potential that is infinite below z=0 and V=mgz for positive z.

Homework Equations

TISE:
\psi \text{''}[z]+\frac{2 m}{\hbar }(\text{En}-V[z])\psi [z]==0

The Attempt at a Solution

First I defined the potential as
V[z]=\text{Piecewise}[\{\{\infty ,z<0\},\{m g z,z\geq 0\}\}];

Then I told Mathematica to solve the Diffeq
\text{DSolve}\left[\left\{\psi \text{''}[z]+\frac{2 m}{\hbar }(\text{En}-V[z])\psi [z]==0,\psi [0]==0,\psi [\infty ]==0\right\},\psi [z],z\right]

The error mathematica gave me was
InverseFunction::ifun: Inverse functions are being used. Values may be lost for multivalued inverses. >>

I'm not really sure how to get mathematica to give me the solution. I know I need 2 conditions besides the differential equation in order to solve. The only boundary condition that I know to use is that the wavefunction must be zero at z=0 since the potential is infinite there.

Any ideas on what second boundary condition I should use or any ideas on where I'm going wrong? Thanks

 

[vela]

It might be choking, in part, on the infinite potential. You know the wavefunction vanishes there, so try using V(z)=mgz and solve for just z>0.