In Fig. we provide the flowchart of the numerical part of our analysis which concerns mainly the determination of the orbital size α -1 in the interacting (correlated) state and, in effect, of the optimal ground state energy and all other bonding-state characteristics. /ST3/02646 and No. UMO-2021/41/B/ST3/04 070 from Narodowe Centrum Nauki. Discussions with our colleague from Theoretical Chemistry Department, Prof. Ewa Brocławik and dr hab. Mariusz Radoń from Inorganic Chemistry Department of the Jagiellonian University are gratefully acknowledged. The authors are also grateful to Prof. Jurgen M. Honig from Purdue University for his critical reading of the manuscript. The final result is the expression (1), which contains single-particle molecular wave functions {w i (r)} i=1,2 .