Binding/antibinding analyses for diatomic interactions. the HeH2= system

On the basis of the Berlin diagram, the region-functional contribution of the electron density has been quantitatively examined for the Is, 2p, and 2p states of HeH²⁺ system. The binding and antibinding contributions and the dynamic behaviours of the electron density during the interaction processes are discussed in comparison with the previous results for homonuclear H₂⁺ system. The effect of coordinate-dependence of the Berlin diagram on the regional partitioning has also been studied.