Model Core Potentials: Development and Applications

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Chemical reactions depend on the interactions between valence electrons, as shown in the columns of the Periodic Table of the elements, where families of chemically related atoms share identical valence electron configurations. In theoretical/computational chemistry, this property gave rise to pseudopotential methods that eliminate the chemically-inert core electrons, reduce computing time, and allow for the studies of very large molecules which contain heavy atoms.***In our laboratory we developed an advanced version of the pseudopotential method, the model core potential (MCP) method. The MCP method allows for accurate predictions of properties and interactions in small molecules, medium-size organometallic complexes, and systems of biochemical importance. The method has demonstrated its predictive power by describing properties of new molecules before they were discovered experimentally. ***Our long-term goal is to advance the MCP methodology by:***• preparing MCP parameters for the studies of excited states and NMR parameters***• developing MCP code that will be speeded up by using Graphics Processing Units***• designing novel molecular systems using the MCP method. ***Short-term objectives in several areas of applications will include:***• Excited electronic states of molecules and molecular ions: We will explore the low-lying excited electronic states of large molecules containing heavy atoms. We will design novel sulfur-substituted crown ethers which, when tethered to a fluorophore, will induce fluorescence that depends on the identity of the heavy metal ion thus aiding in the detection of the ion. ***• Chemistry of rare gas atoms: we will explore the chemistry of radon to identify molecules that might be good candidates for experimental synthesis and detection. We will obtain data about structure, vibrational harmonic and anharmonic spectra, and electronic spectra.***• Interactions between heavy metal ions and organic molecules. We will analyze energetics of reactions between the environmentally-friendly glycolipid biosurfactants that are capable of extracting toxic heavy metal ions. We will determine the effects of metal ions on the structure and spectra of solvated molecules.***• Design of new antimitotic anti-cancer drugs: A better understanding of the interactions between microtubules and ligands is critical in the design of improved drugs. These molecular systems are very large. Fortunately, not all parts of these systems are equal: important chemistry takes place only in a small part of them while the rest merely forms a molecular framework. In the analysis of interactions we will use the new MCPs together with fragment molecular orbital method in molecular dynamics simulations.***Realization of our goals will give the HQPs opportunities to create new theoretical models and apply them to practical problems.***The new MCP parameters and code will be available in the open-source program GAMESS.