Hello PF members, I am trying to solve for helium atom ground state by using perturbation theory. It is very easy to calculate the first order correction of ground state energy but I have no idea for how to find its wave function. I have tried to use the first order correction formula for wave functions in Griffiths' book but it is very hard to take those integrals since it includes very complicated terms like spherical harmonics and Laguerre polynomials etc. Can anyone help me please? Thanks in advance.