화학공학소재연구정보센터
Journal of Physical Chemistry A, Vol.123, No.24, 5019-5026, 2019
Chemical Dynamics Simulations on Association and Ensuing Dissociation of a Benzene-Hexafluorobenzene Molecular System
Chemical dynamics simulations are performed to study the association of benzene (Bz) and hexafluorobenzene (HFB) followed by the ensuing dissociation of the Bz-HFB complex. The calculations are done for 1000, 1500, and 2000 K with an impact parameter (b) range of 0-10 angstrom at each temperature. Almost no complexes are observed to form at b = 8 and 10 angstrom. Following three different methods of calculation of the temperature-dependent association rate constant k(asso)(T), the values obtained are 1.67 x 10(-10), 1.86 x 10(-10), and 2.05 x 10(-10) cm(3)/molecule.s with a standard deviation of approximately 0.1 x 10(-10) cm(3)/molecule.s for T = 1500 K. Among those values of k(asso)(T), the middle one is obtained by considering a relative translational energy of 3RT/2 at T = 1500 K, and the same is followed to calculate k(asso)(T) at 1000 and 2000 K. The Arrhenius parameters, using the k(asso)(T) values at three temperatures, are 0.203 x 10(-10) cm(3)/molecule.s for the pre-exponential factor and -5.79 kcal/mol for the activation energy. The absolute value of the latter is similar to the Bz + HFB association energy of 5.93 kcal/mol. The ensuing dissociation dynamics of the complex is significantly different from the unimolecular dissociation dynamics, and an exponential function fits the N(t - t(0))/N(t(0)) curves comparatively well. The ensuing dissociation is also observed to be independent of time for a statistically large sample size.