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

Proton transfer in malonaldehyde:

anharmonics effects

Nadja Doslic and Darko Babic

Rudjer Boskovic Institute, POB 180, HR-10002 Zagreb, Croatia

Proton transfer dynamics in malonaldehyde (MA) is investigated. Three dimensional potential energy surfaces spanned by the O..H..O fragment of MA were generated based on the Density Functional Theory (DFT) and reparameterized semiempirical calculations. The energy splittings of 42.3 (15.3) cm^-1 and 24.3 (5.3) cm^-1 at the DFT and semiempirical levels, respectively, are in good agreement with the experimental values. The splitting is reduced to 36.4 (12.56) cm^-1 and to 18.6 (2.9) cm^-1 by introducing an effective mass for the heavy atoms. We show that the potential barrier of 4.0 kcal/mol is consistent with the observed H(D) tunnelling splitting of 21.6 (2.9) cm^-1.