Non-Born-Oppenheimer Spectroscopy of Cyclic Triatomics.

摘要

This project involved theoretical and computational studies of quantum dynamics and spectroscopy in the presence of conical intersection, where the Born-Oppenheimer approximation fails due to a very significant geometric phase effect. The focus was on cyclic-N3. Spectroscopy of this radical was studied in great detail, which included construction of its potential energy surface and dipole moment function in the entire configuration space around the conical intersection, accurate calculations of its vibrational states using the state-of-the-art approach (gauge theory), detailed analysis of the geometric phase effect, calculation of transition intensities and, finally, prediction of its infrared spectrum. A simplified treatment of the pseudo- rotational spectrum has also been proposed, based on perturbation theory, which should help to analyze experimental spectrum of cyclic-N3 (when it becomes available) and identify this mysterious molecule in the lab. It should also allow deriving major properties of potential energy surface of cyclic-N3 directly from the experimental data. In addition, new global potential energy surface for O3 molecule (ozone) was developed using high level ab initio electronic structure theory and the fitting by permutationally invariant polynomial functions. Another application of this fitting method was the construction of potential energy surface for molecular anion HCO( ).