Our research is driven by the desire to develop methods that give new perspectives on the nature of interactions between molecules from fundamental principles. Accurately predicting interactions between molecules is the foundation for characterizing their influence on the nature of gases, liquids and solids from a small molecule such as hydrogen bromide to intricate dynamics associated with DNA and protein folding. Our current research involves a state-of-the-art in-house program including innovative spectroscopic techniques and molecular calculations run on supercomputers. These semi-empirical approaches are capable of predicting intermolecular properties in prototypical interactions with uncertainties orders of magnitude better than previously used methods often revealing fundamentally new and unexpectedly properties.
A variety of instrumentation is used in our research, based on the design and development of non-laser spectrometers for the mm to THz spectral region and infrared quantum cascade lasers (QCLs). Techniques are optimized to generate experimental information for spectroscopic characterization of selected prototypical intermolecular interactions. Such information is then included in our compound-model morphed (CMM) algorithms for generating semi-empirical potential functions. Projects are thus inherently interdisciplinary providing the quantum mechanical basis for characterizing non-covalent interactions with increasing complexity while predicting their properties with unprecedented accuracy.
A major current interest in our investigations is to provide a fundamental unified approach to bonding. Enhancements in predictability using CMM have now revealed pairwise canonical transforms providing a flexible, comprehensive and compact way to represent interatomic interactions. It is now available for modeling of van der Waals interactions, hydrogen bonding, halogen bonding, ionic and covalent bonding for a wide range of phenomena found in a diverse variety of problems involving molecular dynamics, thermodynamics, adsorption and phase transitions. We are particularly interested in transforming this discovery to elucidate the complexities of dimensionally larger interactions.
Current Projects involve:
- Spectroscopic studies of interactions between molecules that focus on advancing quantitative characterization of hydrogen bonding and related phenomena including open shell systems.
- Design and development of high resolution quantum cascade laser and solid - state non-laser Terahertz instrumentation and techniques that reveal fundamentally new experimental information on intermolecular interactions.
- Force-based canonical approaches originating from the Hellmann-Feynman and Virial Theorems. Fundamental investigations of chemical bonding through mathematical transformations in molecular quantum mechanics [in collaboration with J.R. Walton, Mathematics Department and R.R. Lucchese.]
- Semi-empirical compound-model morphing methodologies are developed so that vibrationally-complete potentials can predict intermolecular properties to near spectroscopic accuracy as well as discovery of new weakly bound phenomena. [In collaboration with R.R. Lucchese]
- Previously described instrumental developments are being directed to produce THz sensors capable of attomolar or even single molecule detection. Future applications will involve homeland security, medical diagnostics and monitoring, environmental pollution and other applications in analytical chemistry with potential commercialization.
- Interdisciplinary projects with collaborations at both national and international levels that enhance the careers of students in our group. Laboratory investigations of prototypical interactions also focus on the role of NO in bio-regulatory function and H2O complexes significant for modeling phenomena associated with the Earth's atmosphere and climate.
J.R. Walton, L.A. Rivera-Rivera, R.R. Lucchese, J.W. Bevan, "A Canonical Approach to Multi-dimensional van der Waals, Hydrogen-Bonded, and Halogen-Bonded Potentials", Chemical Physics in press (2016).
J.R. Walton, L.A. Rivera-Rivera, R.R. Lucchese, and J.W. Bevan, "Canonical Approaches to Applications of the Virial Theorem", J. Phys. Chem. A in press (2016).
J.R. Walton, L.A. Rivera-Rivera, R.R. Lucchese and J.W. Bevan, "From H2+ to the Multidimensional Potential of the Intermolecular Interaction Ar.HBr: A Canonical Approach", Chem. Phys. Lett. 639, 63-66 (2015).
J.R. Walton, L.A. Rivera-Rivera, R.R. Lucchese and J.W. Bevan, "A General Transformation to Canonical Form for Potentials in Pairwise Interatomic Interactions", Phys. Chem. Chem. Phys. 17, 14805-14810 (2015).
J.R. Walton, L.A. Rivera-Rivera, R.R. Lucchese, J.W. Bevan, "Canonical Potentials and Spectra within the Born-Oppenheimer Approximation", J. Phys. Chem. A, 119, 6753-6758 (2015).
S.D. Springer, B.A. McElmurry, Z. Wang, I.I. Leonov, R.R. Lucchese, J.W. Bevan and L.H. Coudert, "The Rovibrational Analysis of the Water Bending Vibration in the Mid-Infrared Spectrum of Atmospherically Significant N2-H2O Complex", Chem. Phys. Lett. 113, 249-257 (2015).
K.W. Scott, B. A. McElmurry, I.I. Leonov, R.R. Lucchese, J.W. Bevan, "Experimental Confirmation of Ground State Isotopic Isomerization from OC-HI to OC-ID", Chem. Phys. Lett. 619, 174-179 (2015).
R.R. Lucchese, C.K. Rosales, L.A. Rivera-Rivera, B.A. McElmurry, J.W. Bevan and J. R. Walton, "A Unified Perspective on the Nature of Bonding in Pairwise Interatomic Interactions", J. Phys. Chem. A, 118, 6287-6298 (2014).
L.A. Rivera-Rivera, B.A. McElmurry, K.W. Scott, R.R. Lucchese, and J.W. Bevan,
"The Badger-Bauer Rule Revisited: Correlation of Proper Blue Frequency Shifts in the OC Hydrogen Acceptor with Morphed Hydrogen Bond Dissociation Energies in OC-HX (X=F, Cl, Br, I, CN, CCH)", J. Phys. Chem. A. 117 8477-8483 (2013).