A ecessary and Sufficient Condition for The Stability of General molecular Systems

We study here the binding of atoms and molecules and the stability of general molecular systems including molecular ions. This is the first paper of a series devoted to the study of these general problems. We obtain here a general necessary and sufficient condition for the stability of general molecular ststem in the context of thomasz-Fermi-Von Weiasacker, Thomas-Fermi-Dirac-Von Weizsaacker, Hartree or Hartree-Fock theories SUMARY OF PART 1 1.Introduction. II.Presentation of the models III.Diatomic molecular systems and hartree-Fock theory IV.Diatomic molecular systems and Hartree or Thomas-Fermi theories V.General molecular systems Appendix 1: Hartree-Fock models when Z > N ― 1 Appendix 2: Dichotomy yields equal Lagrange multipliers Appendix 3: The problem at infinty for the TRDW model