Internal motion of benzene. A molecular dynamics simulation study

The internal motion of benzene is studied in the gas phase at 30 and 300 K and in the liquid phase at 300 K by means of a molecular dynamics method based on a hybrid of quantum and molecular mechanical force fields. The fluctuations of bond lengths, bond angles and torsional angles are calculated and compared with available experimental data. A conformational analysis for the planar, boat, chair and twisted structures of benzene is carried out and liquid benzene is found to be effectively a planar hexagon at room temperature.