The magnetizability of excited state hydrogen

Abstract

Components of the magnetizabilities of the a ³Σ _g ⁺ and B ¹Σ _u ⁺ states of the hydrogen molecule have been calculated for a wide range of bond lengths. Explicitly correlated, generalized James-Coolidge type wavefunctions were used. It is found that in the B ¹Σ _u ⁺ state the molecular magnetizability is a positive quantity for bond lengths near equilibrium due to the mixing in of the nearby C ¹Π _u state by the magnetic field. As a result van Vleck paramagnetism exists in the low-lying vibrational levels of the B state. At larger bond lengths this mixing is reduced due to an increasing energy denominator and, because of the very shallow potential well for this state, we predict that the paramagnetism will disappear for vibrational states v > 10 for H₂ and v > 12 for D₂.

In the a ³Σ _g ⁺ state the magnetizability is always negative as there exists no close ³Π _g state which could be mixed into the a state by the magnetic field. However, it is an order of magnitude greater than for the ground state due to the greater distances of the electrons from the nuclei. The rotational magnetic moment of the B state is very large and is due predominantly to the electrons. This contrasts with the a state in which the rotational magnetic moment is caused predominantly by the nuclei, as for the ground state.