68 research outputs found
First principle electronic, structural, elastic, and optical properties of strontium titanate
We report self-consistent ab-initio electronic, structural, elastic, and
optical properties of cubic SrTiO perovskite. Our non-relativistic
calculations employed a generalized gradient approximation (GGA) potential and
the linear combination of atomic orbitals (LCAO) formalism. The distinctive
feature of our computations stem from solving self-consistently the system of
equations describing the GGA, using the Bagayoko-Zhao-Williams (BZW) method.
Our results are in agreement with experimental ones where the later are
available. In particular, our theoretical, indirect band gap of 3.24 eV, at the
experimental lattice constant of 3.91 \AA{}, is in excellent agreement with
experiment. Our predicted, equilibrium lattice constant is 3.92 \AA{}, with a
corresponding indirect band gap of 3.21 eV and bulk modulus of 183 GPa.Comment: 11 pages, 6 figures,Accepted for publication in AIP Advances (2012
Study of off-diagonal disorder using the typical medium dynamical cluster approximation
We generalize the typical medium dynamical cluster approximation (TMDCA) and
the local Blackman, Esterling, and Berk (BEB) method for systems with
off-diagonal disorder. Using our extended formalism we perform a systematic
study of the effects of non-local disorder-induced correlations and of
off-diagonal disorder on the density of states and the mobility edge of the
Anderson localized states. We apply our method to the three-dimensional
Anderson model with configuration dependent hopping and find fast convergence
with modest cluster sizes. Our results are in good agreement with the data
obtained using exact diagonalization, and the transfer matrix and kernel
polynomial methods.Comment: 10 pages, 8 figure
Re-examining the electronic structure of germanium: A first-principle study
We report results from an efficient, robust, ab-initio method for
self-consistent calculations of electronic and structural properties of Ge. Our
non-relativistic calculations employed a generalized gradient approximation
(GGA) potential and the linear combination of atomic orbitals (LCAO) formalism.
The distinctive feature of our computations stem from the use of
Bagayoko-Zhao-Williams-Ekuma-Franklin (BZW-EF) method. Our results are in
agreement with experimental ones where the latter are available. In particular,
our theoretical, indirect band gap of 0.65 eV, at the experimental lattice
constant of 5.66 \AA{}, is in excellent agreement with experiment. Our
predicted, equilibrium lattice constant is 5.63 \AA{}, with a corresponding
indirect band gap of 0.65 eV and a bulk modulus of 80 GPa. We also calculated
the effective masses in various directions with respect to the point.Comment: 10 Pages, 3 Figures, and 1 tabl
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