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Ortiz Quantum Chemistry Group

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Research Opportunities for Students, Postdoctoral Fellows and Visitors

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Molecular orbital theory is a powerful conceptual tool for understanding structure and bonding, but it neglects electron correlation. Electron propagator theory provides a framework for the systematic inclusion of electron correlation in a one-electron picture of molecular electronic structure. Propagator calculations produce Dyson orbitals and correlated electron binding energies without determining wavefunctions and energies of individual, many-electron states. Correlated electron binding energies are generalizations and improvements over molecular orbital energies, whereas Dyson orbitals (also known as Feynman-Dyson amplitudes) are the correlated generalizations of molecular orbitals. Several approximate propagators are accurate and efficient tools for the computation of vertical and adiabatic electron binding energies. The association of Dyson orbitals to electron binding energies facilitates interpretation of electronic structure in terms of one-electron concepts. Using electron propagator theory, it is possible to perform accurate, predictive calculations which also yield a qualitative picture of electronic structure.

The concepts and techniques of chemistry change from one generation to the next. Computers and quantum theory now provide information on molecular structure and properties that is often unobtainable by experimental means. The scope of applications is constantly expanding; for example, predictive studies of biologically significant molecules are now feasible with accurate, ab initio methods. For this reason, chemists with theoretical and computational skills are now found in a variety of industrial, government, and academic settings.

Graduate students, postdoctoral fellows and visitors learn the methods of quantum chemistry and acquire many computational skills. Close collaboration with senior members of the group and ample facilities enable new students to gain experience rapidly. Creativity is developed by encouraging independently formulated projects. A given individual's research may emphasize method development or chemical applications.

Applications to chemistry

  • fragments of DNA and RNA
  • polypeptides
  • metalloporphyrins
  • double Rydberg anions
  • organometallic complexes
  • multiply charged anions
  • solvated anion clusters
  • metal, semiconductor and metal oxide clusters
  • photoionization intensities

Derivation and programming of new theory

  • electron propagator theory of ionization energies and electron affinities
  • propagator theory of electron pair binding energies
  • polarization propagator theory of excitation energies and response properties