1. The problem statement, all variables and given/known data I have the particle in the infinite square well and need to calculate the first order correction energy and the wave function. L is the width and the potential is: 1/2 mw2x2 in the -L/2 < x < L/2 and infinity in x <= -L/2 and x>=L/2 2. Relevant equations H'=H-H0 3. The attempt at a solution I have stated that the perturbed Hamiltonian is equal to 1/2 mw2x2. I am confused by the integral itself; I am not sure which boundaries to use. I am assuming that since the potential is infinite in L/2 and -L/2 I am not supposed to use those boundary conditions?