ITR: Collaborative Research:[ASE]-[SIM]: Dissociative Recombination of Astrophysically Important Polyatomic Molecules

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The project aims to extend the ability of theory to predict quantitative rates for the destruction of polyatomic molecules by electron collision, through the process called dissociative recombination. The goal of this research is to carry out detailed quantum mechanical calculations of the dissociative recombination process that occurs when an electron collides with a polyatomic molecular ion. In almost all studies of this process to date, theoretical descriptions have been forced to resort to models of restricted dimensionality, out of computational necessity. Very recent studies have demonstrated, that the full 3D vibrational motion of a triatomic target molecule can be crucially important in some cases. Specifically, in the scattering of an electron from an H3+ ion, the vibrational angular momentum couples to an incident electron through the Jahn-Teller interaction, resulting in recombination rates orders of magnitude higher than a limited dimensionality model predicts. The present proposal plans to capitalize on a recent theoretical breakthrough, to describe the scattering of a low energy electron from polyatomic molecules, including all degrees of freedom quantum mechanically through a divide-and-conquer computational strategy. If this project is successful, the ability to theoretically describe, and to qualitatively understand, the mechanisms of interacting electron-polyatomic systems will be advanced. Note that the two main arms of this work are: (i) a concerted study of the ab initio quantum chemistry issues, at the level of electronic structure theory in the electron continuum, both with and without electronic resonances present; and (ii) a detailed investigation of the coupled electron and nuclear motions, using as tools (depending on the system) either standard resonance theory when it is adequate, or rovibrational frame transformation and multichannel quantum defect techniques when the most comprehensive treatment is desired.This project is supported by the Divisions of Physics and Chemistry under the ITR Program.