Some unusual electronic precorrelation and correlation effects in the sup(1,3) PIsub(μ) states of the hydrogen molecule

The variation of two-electron properties such as (1/r12), (r12) upon variation of the internuclear distance has been investigated for some excited states of the hydrogen molecule. A non-monotonic behaviour of these quantities in the 3 Pi u state is contrasted with the monotonic behaviour in the 1 Pi u as well as in the 3 Sigma g. The larger correlation energy in the 3 Pi u than in the 1 Pi u is related to the differences in the Pauli precorrelation between them.