Abstract: MATH/CHEM/COMP 2002, Dubrovnik, June 24-29, 2002

Molecular Dynamics Calculations of the IR SPECTRUM OF Benzaldehyde

Tomica Hrenar¹, Roland Mitric², and Zlatko Meic¹

¹Faculty of Science, University of Zagreb, Strossmayerov trg 14, HR-10000 Zagreb, Croatia

²Institut für Chemie, Humboldt Universität zu Berlin, Brook-Taylor-Str. 2, D-12489 Berlin, Germany

Harmonic approximation introduces systematic errors in vibrational analysis. The use of semiempirical or the Hartree-Fock force fields gives generally too high values for vibrational frequencies that must be empirically corrected. The use of the density functional methods decreases the need for this correction of frequencies or the corresponding force constants. On the other hand, calculations of vibrational spectra by molecular dynamics methods do not demand such empirical corrections. Using the Newtonian dynamics, with the calculated semiempirical force fields, we have obtained correlation function of the dipole moment. From this time dependency of the dipole moment one can extract information about infrared (IR) spectra of molecules. The described method is applied to benzaldehyde, which is a proper molecule due to its size and availability of experimental data. The obtained results will be presented and discussed.