[PAST EVENT] Physics Colloquium

November 6, 2015
4pm - 5pm
Small Hall, Room 111
300 Ukrop Way
Williamsburg, VA 23185Map this location
Molecular magnets generally consist of a collection of transition-metal ions that have five to six nearest-neighbors. Due to this high-coordination, the d-level filling associated with the transition metal centers is often unambiguously determined by the ligands surrounding the metal center. As such, gradient corrected density-functionals, such as PW91 and PBE GGA[1], have proved to be very successful for describing such molecules[2]. However, improvements in these functionals are necessary if one is interested in obtaining quantitatively accurate spin excitations in molecules containing low-coordination 3d transition metal ions or, for other reasons, one is interested in understanding electronic transport across such molecules. In this talk, I review some of the general improvements that have been offered by the Perdew-Zunger self-interaction correction (SIC) and past approaches to solving these equations[3]. A new version of the self-interaction correction to density functional theory, based upon Fermi Orbitals, is briefly introduced[4-5] which seems to be simpler to use and which provides two formal improvements over the original version. Further, the formalism identifies quasi-classical electron positions that seem to be in accord with conventional classical models for electrons in molecules. Applications of this self-interaction-corrected theory, within the local spin-density approximation, give improvements to atomization energies of molecules, total energies and ionization energies in atoms, and the uniform electron gas is obtained. By example, it is shown that the method is fast enough to apply to systems with open metal centers[6].

[1] J. P. Perdew, J. A. Chevary, S. H. Vosko, K. A. Jackson, M. R. Pederson, D. J. Singh, and C. Fiolhais, Phys. Rev. B 46, 6671 (1992).
[2]N.A. Zimbovskaya and M.R. Pederson, Physics Reports 509 (1-87) (2011).
[3]M.R. Pederson, R.A. Heaton, and C.C. Lin, J. Chem. Phys. 82, 2688 (1985).
[4]M.R. Pederson, A. Ruszinzsky and J.P. Perdew, J. Chem. Phys. 140, 121105 (2014).
[5]M.R. Pederson, J. Chem. Phys. 142, 064112 (2015).
[6]M.R. Pederson, T. Baruah, D.Y. Kao and L. Basurto (To appear).