General type of a uniform and reversible representation of chemical structures

In any type of modelling (be classical or by artificial neural networks) involving chemical structures and their corresponding properties, the first problem encountered is the representation of chemical structures. A good structure representation should have different code for each 3-D structure (uniqueness), it should have the same number of variables for all structures, it should be reversible, and should be translation and rotational invariant. In the present contribution we are discussing a new method for representing chemical structures which, at least in principle and within limitations bound to the precision and resolution of the projection, fulfils all mentioned requirements with the exception (in some cases) of the rotational invariance. The discussed representation is based on the projections of atoms on the sphere with an arbitrary radius. The new structure representation of a molecule with N atoms is defined as n-dimensional vector S = (s 1 ,s 2 ,..s i ,...s n ) with each component defined as a cumulative intensity s i , at a given point i on the circle with and arbitrary radius. The cumulative intensity s i (the i-th point on the circle at angle ϕ i .) is a sum of N contributions I(i,ρ j ,ϕ j ) from each atom j in the molecule.