Rotational Relaxation in Polar Gases. III. Molecular Dynamics

Abstract

A 50 molecule sample in contact with a heat bath of similar molecules was used as a model to calculate the rotational collision numbers, Zrot, for HCI and DCI at 300 and SOOoK, by the method of molecular dynamics. The mean rotational energy of the sample exhibits an exponential approach to a steady state value; however, there was considerable scatter about the exponential curve. The results for Zrot generally agree with previous theoretical calculations. They are intermediate to experimental acoustic data and the earlier perturbation results. second, and fourth moments of angular momentum and Boltzmann's H function, the second moment being essentially the kinetic energy. They experienced difficulties in extracting relaxation times because of large fluctuations. An interesting aspect of this work is the demonstration of the existence of a set of initial 4523

Dynamics of Weak and Strong Collisions: Highly Vibrationally Excited Pyrazine (E = 37900 cm−1) with DCl

“…The collision integral Ω (2,2) * is Ω (2,2) * = 1.16145( T *) −0.14874 + 0.52487exp (−0.7732 T *) + 2.16178exp (−2.43787 T *), where T * = T /(ε/ k B ) . Used were the following parameters: σ DCl = 3.36 × 10 −10 m (ref ), (ε/ k B ) DCl = 328 K (ref ), and σ Pyz = 5.35 × 10 −10 m, (ε/ k B ) Pyz = 435.5 K (ref ).…”

Nonequilibrium Effects in Atomic Recombination Reactions

“…The procedure which is adopted consists in approximating the evolution of the system from a specified initial state by a sequence of trajectory calculations. 4 The method is described and justified in Sec. II.…”