John Morrison
University of Louisville, USA
Title: Accurate first-principle calculations of the spectra of diatomic molecules in planetary atmospheres
Biography
Biography: John Morrison
Abstract
A summary will be given of various approaches that can be used to perform numerical Hartree-Fock method and many-body calculations on atoms and molecules. The theoretical approaches considered include the multi-configuration Hartree-Fock method and many-body perturbation theory. For light atoms and molecules, more than 98 percent of the correlation energy is due to pair excitations. Because molecules lack spherical symmetry, Schrodinger-like equations for molecules typically involve many more independent variables. While, the Hartree-Fock equations for atoms involve a single radial variable and the two-electron pair equation for atoms involve two radial variables, the Hartree-Fock equations for diatomic molecules involves two independent variables and the pair equation for diatomic molecules involve five independent variables. To deal with these problems of higher-dimensionality, my mathematical collaborators and I have developed numerical methods for dividing the variable space into smaller sub-regions in which the equations can be solved independently. This domain decomposition theory is described and numerical results are given for Hartree-Fock calculations for diatomic molecules and for numerical solutions of the first-order pair equations which can be used to evaluate the Goldstone diagrams that arise in many-body calculations of molecular spectra. The goal of our calculations is to describe the energy of two helium atoms approaching each other in a cold atomic collision and to obtain the spectral fingerprints of CO and OH molecules in planetary atmospheres.