I am interested in the topic of the thread https://www.physicsforums.com/showthread.php?t=768539 ,especially for those unpair 1p1n case. As I know, for the simplest case deuteron, the Jπ (groundstate here and later) is 1+ but 0+. This is very different to the atomic physics case. For He atom, 2 electron create the 1S0 groundstate. For 18F, it is again 1+, although n and p are in the same orbital d5/2, which can combine the possible 0+,1+,2+,3+,4+,5+. For 50V is 6+. Could someone help to explain? Is there theory for the 1p1n structure?