Quantum Mechanics of Beryllium Hydride

The interaction of a normal hydrogen atom with a beryllium atom having the electronic configurations $2s2s$ and $2s2p$, respectively, has been studied by the application of a modified Heitler-London method. It is shown that for beryllium in the ¹S atomic state, the resulting ²Σ molecular state is repulsive. For beryllium in the ³P atomic state, the ⁴Π and ⁴Σ molecular states are repulsive, and the ²Π and ²Σ states are attractive. For beryllium in the ¹P atomic state both the ²Π and ²Σ molecular states are found to be repulsive. However, when the interaction between the ²Σ(³P+²S) and the ²Σ(¹S+²S) molecular states is taken into account the lowest ²Σ state is found to be attractive. The calculated heats of dissociation for the attractive states are in poor agreement with the extrapolated values from the band system.