1. The problem statement, all variables and given/known data A particle is constrained by walls that form a cubic box. Obtain the wavecuntions and the energies. 2. Relevant equations This is a summary of the solutions: http://quantummechanics.ucsd.edu/ph130a/130_notes/node202.html Here there is also some info: http://en.wikipedia.org/wiki/Particle_in_a_box#Higher-dimensional_boxes 3. The attempt at a solution I've managed to obtain the correct solution, but I didn't know how to state the boundary conditions and I had to decide the values of the constants using "intuition". Could you explain me how would the BC look like in this scenario? Thank you for your time.