Computational Chemistry: From small molecule quantum dynamics to new materials - Alex Brown

In this talk, I will present our recent work on detailed understanding of the dynamics of small (3-4 atoms) polyatomic molecules to the physical and photophysical properties of large inorganic species. The research will showcase a variety of electronic structure methods and dynamics techniques that can be utilized for understanding problems in molecular, optical, and nanoscale physics. In the first part of my talk, I will discuss optimal control theory and the multi-configuration time-dependent Hartree (MCTDH) technique for quantum dynamics. Prior to tackling the quantum dynamics, one requires a high quality multi-dimensional potential energy surface (PES), and, in order to exploit fully the numerical efficiency of MCTDH, the PES must be fit to sum-of-products form. I will discuss our fitting of PESs to a sum-of-products form using the neural network method with exponential neurons. I will highlight the approach using fits of CS2, HFCO, and HONO PESs based upon high-level ab initio data. Using a generic interface between the neural network PES fitting and the Heidelberg MCTDH software package, the PESs have been tested via comparison of vibrational energies to experimental measurements. In the second part of my talk, I will highlight recent examples from our work on phosphorescent tellurophene-compounds and molecular precursors for materials chemistry (research in collaboration with Prof. E. Rivard, University of Alberta). I will demonstrate how new insight can be obtained via a variety of electronic structure methods including time-dependent density functional theory, atoms-in-molecules (AIM), and natural bond order (NBO) approaches.