THEORETICAL DETERMINATION OF STRUCTURAL PARAMETERS FOR S-TRIAZINE ANDSOME DERIVATIVES - COMPARISON BETWEEN ABINITIO AND SEMIEMPIRICAL CALCULATIONS

The structures of s-triazine and some derivatives have been determined by ab initio computations with the 6-3 1 G and Dunning basis sets aug mented by polarization functions. The effect of addition of the polari zation functions as well as correlation effects, using a Moller-Plesse t procedure, is analyzed. Comparison is made with experimental data an d other calculations available from the literature. Basis set effects are evaluated. Moreover, a comparison is made with semi-empirical calc ulations using the AM1 method. Such semi-empirical methods are widely used for the study of compounds of biological or chemical interest and such a comparison provides an evaluation of the approximation involve d in these methods.