Catastrophe Theory in Chemistry Ⅰ. The Structural Behaviour Stability of Diatomic Molecules

Catastrophe theory is a new mathematical one which is used to deal the singularity of a family of smooth functions and discontinual phenomena,its main mathematical foundation is to analyse the discontinual behaviour of potential function in the neighbourhood of variour critial points by using the surface theory, and to build up mathematical models by synthesizing all experiment material, then to probe into the essence of things and to predict the mechanism.
Based on the conclusion of Quantum Chemistry and experiment, three postulates are made and the structural model to analyse diatomic structural behaviour stability is built up in this paper. In not solving Schrodinger equation, the potential is expressed by using the fold-catastrophe theory. It is noted that the effect orbital interaction between atoms is the essential prerequisite of molecular stable existence in control space. The inner nature of molecular existence and the relative relationship between the numbers of bond and bond length in molecules are demonstrated and the molecular equilibrium potential expression is given, it coincide in the conclusion of Quantum Chemistry and experiments. If the bond parameter A is endowed with a large amount of chemical information, the results will be more reasonable.