Ab initio molecular orbital analysis of acetaldehyde dimers.: Thermodynamic properties

The surface of the acetaldehyde dimer was studied by MP2/6-31+G* ab initio calculations and some of the minima thus located were used in subsequent optimizations and single-point calculations at the B3-LYP/6-311+G(2d,p), MP2/6-311+G(2d,p), MP2/aug-cc-pDVZ and MP2/aug-cc-pTVZ levels. An overall of six minima in two distinct groups were detected, one group consisting of planar configurations and the other of more stable, non-planar (spatial) configurations of the two monomers. Some of the dimer thermodynamic properties were calculated from its harmonic frequencies and a comparison between the experimental values for the thermodynamic properties and the calculated values is discussed.