Abstract: MATH/CHEM/COMP 2002, Dubrovnik,
June 2429, 2002

Molecular Dynamics
Calculations of the IR SPECTRUM OF Benzaldehyde
Tomica Hrenar^{1}, Roland Mitric^{2}, and Zlatko Meic^{1} ^{1}Faculty of
Science, University of Zagreb, Strossmayerov trg 14, HR10000 Zagreb, Croatia ^{2}Institut für Chemie, Humboldt Universität zu Berlin, BrookTaylorStr. 2, D12489 Berlin, Germany Harmonic approximation introduces systematic errors in vibrational analysis. The use of semiempirical or the HartreeFock 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. 