AB-INITIO MOLECULAR STUDY OF HYDROGEN-PEROXIDE - APPLICATION OF DENSITY-FUNCTIONAL METHODS

A systematic study of the abilities of a broad family of density funct ional methods and basis sets has been carried out on hydrogen peroxide . Calculations have been performed using different basis sets from 3-2 1G to 6-311 + G(3d, 2p). Various local and non-local exchange, exchang e-correlation and hybrid functionals have been applied in order to stu dy the structure, energetic and vibrational properties of hydrogen per oxide. Comparison with experimental data and also with results from ab initio methods (HF and correlated levels) shows a good performance of non-local density functional methods for the description of the hydro gen peroxide geometry, especially the torsion angle tau, when we use b asis sets of sufficient quality (at the least basis sets with a polari zation function on oxygen). Different density functionals have been us ed in order to study cia and trans rotational transition states, using 6-31G(2d,p) and 6-31 + Cr(2d.p) basis sets. The calculated torsional barriers and zero-point vibrational energies (ZPEs) are in very good a greement with experimental values. (C) 1998 Elsevier Science B.V. All right reserved.