Furan and acetic acid 1∶1 complex was subjected to density functional theory calculations using 6-311＋＋G(d,p) basis set. Six equilibrium isomers were located on the potential energy surface. The most stable structure has a strong O…H—O hydrogen-bonding interaction, and the calculated bonding energy of it is －20.87 kJ•mol^－1. A normal-mode analysis of the vibrations of the six isomers was carried out. The solvent effects on the geometries of equilibrium isomers and dipole moments were systematically studied by self-consistent reaction field technique with different dielectric constants of 1.0, 2.247, 4.9, 7.58, 10.36, 20.7, 32.63, 38.2, 46.7 and 78.39. It was found that the solvent effect would enhance significantly the strength of hydrogen bond as shown by the decrease of the O…H distance and appreciable red shift of the H—O vibration mode. The solvent effect was obvious when ε was in 1.0～32.63 and was weak when ε exceeded 32.63.

Key words: density functional theory, furan-acetic acid complex, basic set superposition error, SCRF