perturbation theory, variational principle Hello everyone, I'm new to this place. This is cut-and-pasted from another forum; one of the people over there directed me here. Any help would be appreciated. (I would like to note before you read this that my homework is in fact complete; I'm not asking anyone to DO my homework, just to check my answers. Thanks.) Would someone mind checking my math before I turn this in? In particular, if someone would run the double delta integrals in problem one through Maple or Mathematica I'd really appreciate it. Actually all of the integrals if you have time; I did them with a table rather than with software since I don't have any. The Gaussians I'm pretty comfortable with but the sin^n integrals were pretty annoying. (Except the answer to 3(b), I doubt it's dimensionally correct but I can't find an error in it.) Also, if anyone is familiar with time-independent perturbation theory: did I do number 4 right? It says to first order in epsilon, and I thought it would figure into the power series expansion, but it just comes out of the integral as a constant in the first order correction. The second-order energy correction will have an epsilon squared term in it so this is it. I thought it would be harder than that.