Paul Soven

A green's function theory of surface states

Abstract A Greens function theory of surface states is presented. Starting from the energy eigenvalues of an infinite crystal, we generate the Greens function of a semi-infinite crystal using standard techniques. The effect of alterations in the surface potential is included. With the aid of the Greens function we calculate various local and total densities of states for both bulk (extended) and surface (localized) states. We apply the technique to the case of a non-degenerate band in a simple cubic lattice. The effect of introducing surfaces in various crystallographic directions is studied in detail. Numerical results are presented.

Band structure of polymeric sulfur nitride

Abstract Using the Extended Huckel Method, a band structure calculation of polymeric sulfur nitride based on X-ray crystallographic data has been carried out. The results of the calculation suggest that the metallic properties of (SN) x arise from the accidental overlap of non-symmetry related segments of an anisotropic three dimensional band structure. Our results are similar to those obtained by other investigators using a different crystal structure.

Field emission energy distribution from (111) copper

Abstract Theoretical calculations of the field emission energy distributions from (111) Cu are presented. Both bulk and surface state contributions are considered, with the latter in particular being predicted to be predominant in part of the accessible energy region. The d -band contribution is also considered and shown to be small but clearly observable.

Field emission energy distribution from adsorbate covered tungsten

Abstract We discuss the effect of various classes of adsorbates on the surface states and resonances known to produce structure in the field emission energy distribution from (100) tungsten. We show that it is the overlayer geometry which is of importance in determining whether or not the resonances and concomittant FEED structure persist in the presence of adsorbates. In particular, a c(2 × 2) krypton overlayer destroys the structure while a (1 × 1) gold overlayer does not.

Self‐consistent linear response study of the polarizability of molecular nitrogen

The static polarizability of molecular nitrogen is computed in a local‐density‐functional self‐consistent linear response framework. The work reported here investigates that applicability of a theory of this type to a study of observable response functions and evaluates the utility of a simple approximation to the density–density response function of the molecular system. Computed quantities are in good agreement with experiment.