A modified Rydberg formula

A modification of the Rydberg formula for atomic states is found to give quite accurate energies of terms of the type (core)(ns 2 1 S) for a wide variety of atoms (ground states of negative, neutral and positively ionized atoms, negative-ion resonances, autoionizing levels). It gives, for example, the energies of the lowest negative-ion resonances of the noble-gas atoms to an accuracy of 82 MeV or better, and the electron affinities of the alkali-metal atoms to an accuracy of 100 MeV or better. It can also be applied to other terms of the type (core)(nlnl' 2S+1 L). An extension of the formula gives energies of configurations of the type (core)np N , where N=1-6.