Floppy structure of the benzene dimer : ab initio calculation on the structure and dipole moment

• Published in: The Journal of chemical physics 1990-10, Vol.93 (8), p.5893-5897
• Main Authors: HOBZA, P, SELZLE, H. L, SCHLAG, E. W
• Format: Article
• Language: English
• Subjects: Atomic and molecular physics; Effects of atomic and molecular interactions on electronic structure; Electronic structure of atoms, molecules and their ions: theory; Exact sciences and technology; Physics
• ISSN: 0021-9606; 1089-7690
• DOI: 10.1063/1.459587

The structure of the benzene dimer has aroused considerable interest due to recent experimental measurements and hence extensive theoretical calculation is topical. Nine structures of the benzene dimer were investigated using the second-order Mo/ller–Plesset theory. The calculations were performed with smaller (MIDI-1+s+p) and larger (6-31+G*) basis sets. The T-shape structure was found to be the most stable but with a very shallow minimum; the wagging motion around the lowest hydrogen in the range of ±10° is practically nonhindered. These results together are consistent with the structure found experimentally. The final binding energy for the T structure (distance of molecular centers equal to 5.0 A) is −2.7±0.4 kcal/mol, which is more than the value derived from experiments. The calculated dipole moment is in excellent agreement with experiment.