Characterizing non-covalent interactions and peptide bond formation with electronic structure theory

The development and application of quantum mechanics has exploded in the past century. The rules of classical mechanics were found to be completely insufficient when applied to a universe that operates on the scale of atomic and subatomic particles. The advancement of quantum theory and computer technology has driven quantum mechanical analyses toward routine in the chemist's laboratory.;Chapter 1 briefly outlines some common failures of classical mechanics from a historical.;standpoint. Chapter 2 provides a mathematical overview to quantum chemistry including.;a brief presentation of the analytic solutions to the Schrodinger equation for some model.;systems. Chapter 3 and Chapter 4 introduces some commonly used methods and basis sets, respectively, used in electronic structure theory. Chapter 5 introduces a couple of chemically interesting problems which are examined with quantum mechanical electronic structure methods in this research. Chapter 6 analyzes the weakly-bound, dispersion dominated systems of the P 2 and PCCP homogeneous dimers and the importance of higher-order correlation corrections. Chapter 7 analyzes the low-energy dimers of the homogeneous and heterogeneous dimers of formaldehyde and thioformaldehyde as well as the associated vibrational frequencies. This work highlights some significant deficiencies of density functional theory methods. Chapter 8 examines the condensation reaction of glycine in the gas-phase via four reaction mechanisms. This work indicates that only one mechanism is slightly favored energetically. Chapter 9 summarizes the results of the research presented in this dissertation.