AB-INITIO SELF-CONSISTENT REACTION FIELD CALCULATIONS ON AMINO-ACIDS - ASPARAGINE ZWITTERIONS IN POLAR MEDIUM AND GAS-PHASE

A comparative theoretical study of the structure and vibrations of ami no acid L-asparagine has been performed on the basis of ab initio Hart ree-Fock calculations and the self-consistent reaction field theory. T he 3-21G and 6-31+G* basis sets were used to evaluate quadratic force fields of this amino acid in an aqueous solution and in isolation (ga s phase). Previously each of the minimal energy structures was predict ed. Geometric parameters, atomic charges, electronic energies, vibrati onal frequencies, normal mode descriptions and force constants were co mpared. The results confirmed the 6-31+G as a suitable basis for the study of polar molecules in polar media.