Unified description of chemical bonding in H-2 isotopomers, including Ps(2), mu(2) and bi-excitons

We developed an unified treatment of the low-lying states of the general A( +)A(+)e(-)e(-) systems based on the concepts of chemical bonding, using an intuitive valence bond electronic wavefunction. A reduced mass correction a ccounts for the effects of the finite masses of nuclei A. The potential ene rgy curves, the electronic densities and the ionic contribution show simila r behaviour for all systems. The number of vibrational states versus the ma ss relation lambda is obtained and compared to theoretical predictions. We verified that the use of atomic masses instead of nuclear masses is fundame ntal in order to obtain the only bound state in the cases lambda similar or equal to 1. (C) 2000 Elsevier Science B.V. All rights reserved.