Theoretical study on the structures and energies of acetic acid dimers in aqueous solution

The effects of hydration on the dimerization energies and structures of ace tic acid dimers are studied by the reference interaction site model self-co nsistent-field (RISM-SCF) method. Comparisons of the RISM-SCF results are a lso made with those obtained from the self-consistent reaction field (SCRF) methods to examine the dielectric effects of the solvent. The RISM-SCF met hod predicts the marked stabilization due to solvation in the dimer structu res with large dipole moments. From the decomposition analysis of the exces s chemical potential, the contribution from the free carbonyl oxygen is fou nd to be much larger than the other atoms for the stabilization of these di mers in aqueous solution. Such a stabilization in the polar dimers is not o btained from the simplest SCRF method that considers only the solute dipole .