My question is the following one:
If i have the first excited state of helium, the possibilities for the two electrons are : 1s+,2s+ , 1s+2s-, 1s-,2s- and 1s-,2s+ , where + and - denotes spin up and down. If I use the slater's determinant to generate antisymmetric states, I get :
$$|u1> =...