As students of physics will know,  atomic and nuclear states are labelled using a sequence of letters that has a historical derivation from a time before the underlying physics was fully understood.  Thus the sequence of letters s, p, d, f, g, h, i, j, k, ... correspond to angular momentum values of 0, 1, 2, 3, 4, 5, 6, 7, 8, ... . The letters are known as spectroscopic notation . Sometimes in computer codes it is nice to make the translation between the letter and the number.  Some new-fangled