P558: NBO methods: Finding atoms and orbitals in molecules

Author: Clark Landis, University of Wisconsin-Madison, USA

Co-Author: Frank Weinhold, University of Wisconsin-Madison, USA; Eric Glendening, Indiana State University, USA

Date: 8/5/14

Time: 2:25 PM2:45 PM

Room: MAN 123

Related Symposium: S36

Atoms first approaches are useful only if the concepts are consistent with our best understanding of electronic structure. Atoms first analysis of electronic structures requires that, first, atoms must be located in more complex molecular or condensed phase environments. Natural Bond Orbital (NBO) methods enable unique identification of atoms and their natural atomic orbitals (NAOs) in the molecular environment. NBO analysis may be performed on electronic structures computed with any method that produces a one-electron density matrix. NAOs provide the foundation for building up descriptive concepts such electron configuration, hybridization, atomic charge, bond orbitals, and Lewis structures.

P559: Lewis-like structures: Consistent starting points for describing electronic structures across the periodic table

Author: Clark Landis, University of Wisconsin-Madison, USA

Co-Author: Frank Weinhold, University of Wisconsin-Madison, USA; Eric Glendening, Indiana State University, USA

Date: 8/5/14

Time: 2:45 PM3:05 PM

Room: MAN 123

Related Symposium: S36

Are Lewis structures consistent with high quality electronic structures? Natural Bond Orbital (NBO) analysis of molecules across the periodic table supports the primacy of Lewis-like structures in many small molecules that can encompass exceptional molecules through a consistent and logical donor-acceptor viewpoint. Key to judging the validity of Lewis-like structures is the difference between the ab initio one-electron density matrix and that of the idealized Lewis structure. This metric-of-quality reveals that many concepts – Lewis structures, hybridization, electronegativity, resonance, etc. – originating from pre- and early quantum days, not only survive scrutiny but form the basis for new insights into the structures of transition metal complexes.