The number of pages within the document is: 33
The self-declared author(s) is/are:
David W. Schwenke and Donald G. Truhlar
The subject is as follows:
Original authors did not specify.
The original URL is: LINK
The access date was:
2019-01-22 00:45:51.723656
Please be aware that this may be under copyright restrictions. Please send an email to admin@pharmacoengineering.com for any AI-generated issues.
Loading...
Reload document 
Open in new tab The content is as follows:
CONVERGED CALCULATIONS OF ROTATIONAL EXCITATION AND v-v ENERGY TRANSFER IN THE COLLISION OF TWO MOLECULES David W. Schwenke and Donald G. Truhlar Department of Chemistry and Supercomputer Institute University of Minnesota Minneapolis, Minnesota 55455, U.S.A. ABSTRACT We present the results of large-scale quantum mechanical calculations of state-to-state transition probabilities for the collision of two hydrogen fluoride molecules. We use a potential energy surface obtained by adding a vibrational dependence to the interaction potential of Alexander and DePristo, and we consider zero total angular momentum. Wehave calculated converged transition probabilities for rotational energy transfer in the rigid rota tor approximation and for vibration-to-vibration energy transfer in calculations including full vibration-rotation coupling. The V-V calculations include up to 948 coupled channels. Final production runs were carried out with a highly vectorized code on the University of Minnesota Cyber 205 and Cray-l computers; earlier test runs were carried out as weIl on a Cray Research X-MP/48 machine. 1. INTRODUCTION In molecular quantum mechanics the amount of effort required to treat problems involving systems with two, three, or four atoms increases enormously as each atom is added to the system. The present status in molecular scattering theory is that atom-atom collisions may be treated routinely and atom-diatom collisions may be treated only with great difficulty unless one makes dynamical approximations or artificially restricts or eliminates one or more coordinates.! Exact treatments of four-atom systems are generally considered to lie “beyond the state of the art.” Encouraged by the great computational enhancements afforded by the class VI computers (Le., vector pipeline machines like the Cray-l, the Control Data Corporation Cyber 205, and the Cray X-MP series), we have embarked on a quest to obtain converged results for a prototype diatom-collision. Although it is not the simplest such system we chose HF-HF as the prototype for study. The basic reasoning behind this choice of system is as folIows. First, the number of internal states involved is much smaller for hydrides than nonhydrides. Second, among collisions of hydrides the HF-HF system has been most widely studied experimentally.2 In fact the HF-HF system may even be considered the experimental prototype for vibration-to-vibration (V-V) energy transfer, and V-V energy transfer in turn is the dominant energy relaxation mechanism under most conditions where such relaxation is of interest. Furthermore, there have been several studies of the HF-HF potential energy surface,3 and a knowledge of the potential energy surface is aprerequisite for a dynamics calculation.
Please note all content on this page was automatically generated via our AI-based algorithm. Please let us know if you find any errors.