Ab initio self-consistent reaction field calculations on amino acids: asparagine zwitterions in polar medium and gas phase

Abstract.

A comparative theoretical study of the structure and vibrations of amino acid L-asparagine has been performed on the basis of ab initio Hartree-Fock calculations and the self-consistent reaction field theory. The 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 (gas phase). Previously each of the minimal energy structures was predicted. Geometric parameters, atomic charges, electronic energies, vibrational frequencies, normal mode descriptions and force constants were compared. The results confirmed the 6-31+G* as a suitable basis for the study of polar molecules in polar media.