A DYNAMIC SIMULATION METHOD SUPPRESSING UNINTERESTING DEGREES OF FREEDOM .2. MECHANISM OF PI FLIPS IN A LATTICE OF BENZENE RINGS

Our method [P. Romiszowski and R. Yaris, J. Chem. Phys. 94, 6751, (1991)] of simulating infrequent motions by using an equation of motion with the uninteresting degrees of freedom suppressed-the generalized Langevin equation-has been extended to enable us to obtain the mechanism for the gated transition. The model problem is a two-dimensional array of benzene rings interacting with nearest neighbor potentials and we are looking for the mechanism of the pi-flip transition of the central benzene ring. Thus we retain only the angular coordinates of the central ring and its four nearest neighbors in the generalized Langevin equation. The mechanism obtained for the gating by the nearest neighbor rings is the same both qualitatively and quantitatively in the simulation with a reduced number of degrees of freedom and in the full simulation.