Computational Physics Seminar
Modeling Conductivity Gaps and Closures at the Atomistic Scale
Presented by Steve Valone, Materials Science and Technology Division, Los Alamos National Laboratory
A fragment Hamiltonian (FH) approach is used to construct a model Hamiltonian for systems of two fragments, wherein a fragment is an arbitrary collection of electrons and nuclei. Charge-excitation gap closure is assessed as a test of the FH model for bridging between electronic and atomistic scales. Derivation of FH model yields local values of chemical potentials, as well as several charge hopping integrals, as natural outcomes of the model. Global chemical potentials and gaps are deduced from competitions among these energies. Analyses of a combination of fragment energies show that charge hopping integrals compete with either the Hubbard U or the charge-transfer gap Δ to close conductivity gaps in FH models, depending on the nature of the excitation gap.
3:00 pm, Friday, June 26, 2015
PAIS-2540, PAIS
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