R-matrices, generation and

Let EM(B) and EM(E) be the initial and final ensemble of molecules of a chemical reaction or sequence of reaction. This chemical conversion determines in a characteristic manner a correlation of the atoms in EM(E) and EM(B). We conjecture that chemical reactions proceed in such a manner that a minimum of valence electrons is relocated. This is criterion for the correlation of the atoms of EM(E) to the atoms of EM(B). We call the number of valence electrons which must be relocated during the transformation from EM(B) to EM(E) with a given correlation of atoms the chemical distance D(B, E) between these EM. 

ACS Symposium Series American Chemical Society Washington, DC, 1977. 

For the chemically meaningful representation EM(B) EM(E) the atoms of EM(B) must be assigned to atoms of EM(E) in such a manner that the chemical distance D has its minimal value. 

1) Exhaustive enumeration all atoms with the same atomic number are permuted and the permutation corresponding to the minimal chemical distance is taken. 

This criterion follows from the assumption, that in a reaction each atom will try to maintain as many spheres of neighbors as possible. 

---