Physics Department colloquium is Oct. 9 William Schwalm will present "Model Properties From Green Functions" at the next physics colloquium, 4 p.m. Friday, Oct. 9, in 211 Witmer Hall. To understand electron dynamics in planar organic molecules it is important to study electrons in π orbitals (odd on reflection through the plane). These orbitals tend to be the ones near the Fermi level. There is a very simple mathematical model for this that works to some extent. We will be interested in enormous molecules that might present amorphous structures or nanoscale engineered devices. After outlining some of the theoretical points, I will present results for inhomogeneous structures built from graphene, where graphene is a single graphite layer. Properties discussed include local densities of states (LDOS) possibly relevant to STM, electron scattering from a vacancy or an impurity (with or without spin), electron conductance in Kubo formalism, spectral density for fixed momentum k parallel in the plane of the layer, which might relate to angle resolved photoemission spectroscopy (ARPS) and so on. Time permitting I will also present some results on fractal lattices that may relate to disordered layers. Coffee and cookies will be served at 3:30 p.m., Oct. 9, in 215 Witmer Hall. -- Connie Cicha, Secretary, Physics & Astrophysics, connie_cicha@und.nodak.edu, 777-2911