Metadynamics molecular simulations with accurate quantum chemistry calculation for the study of the anions forms of Malonic Acid

ELIANA K. ASCIUTTO; CELESTE SAGUI

Atlanta

Congreso; American Chemical Society National Meeting 2006; 2006

American Chemical Society

We have determined the optimized structures, relative energies and intramolecular reactions for two anionic forms of malonic acid, anion malonate(-1) (HO2CCH2CO2-) and malonate(-2) (-O2CCH2CO2-). For this purpose we employed accurate quantum chemistry calculations using MP2 theory and Density Functional Theory to determine the structures and energies, and a novel metadynamics method based on Car-Parrinello molecular dynamics for the thermal reactions. For both malonates, we found new isomers (keto and enol structures) characterized by CO2 rotations and intramolecular proton transfers. These proton transfers characterize the keto-enol tautomerism that takes place both in the monoanion and dianion. In all cases, the keto tautomer is the more stable configuration. The metadynamics method allows the system to explore the potential energy surface in a few picoseconds, crossing activation barriers of 20-50 kcal/mol.