52. A 3D APPROACH TO STRUCTURE - INFRARED SPECTRA SIMULATION AND ANALYSIS. J. Gasteiger, P. Slezer, L. Steinhauer, V. Steinhauer, Computer-Chemie-Centrum, Universitaet Erlangen-Nuernberg, Naegelsbachstr. 25, D-91052 Erlangen, Germany.

An empirical approach to the modeling of the relationships between structure and infrared spectra is highly attractive, particularly when large molecules or large datasets have to be treated. We will show that powerful neural network techniques such as a counterpropagation network can model the relationships between structure and IR spectra. Central to this approach is a transformation of the 3D structure of molecules to a novel structure code. (1) This approach allows the simulation of IR-spectra over the entire frequency range as shown with a variety of examples. The counterpropagation network can also be used in reverse mode; by input of an infrared spectrum the 3D structure of a molecule can be predicted. The first examples of 3D structures derived directly from the IR spectrum will be given.