8 research outputs found
Effect of short-range order on the electronic structure and optical properties of the CuZn alloy : an augmented space approach
In this work we have combined the generalized augmented space method
introduced by one of us with the recursion method of Haydock et al (GASR),
within the framework of the local density functional based linear muffin-tin
orbitals basis (TB-LMTO). Using this we have studied the effect of short-range
ordering and clustering on the density of states, optical conductivity and
reflectivity of 50-50 CuZn alloys. Our results are in good agreement with
alternative techniques. We argue that the TB-LMTO-GASR is a feasible, efficient
and quantitatively accurate computational technique for the study of
environmental effects in disordered binary alloys.Comment: 11 pages 11 figure
Augmented space recursion for partially disordered systems
Off-stoichiometric alloys exhibit partial disorder, in the sense that only
some of the sublattices of the stoichiometric ordered alloy become disordered.
This paper puts forward a generalization of the augmented space recursion (ASR)
(introduced earlier by one of us (Mookerjee et al 1997(*))) for systems with
many atoms per unit cell. In order to justify the convergence properties of ASR
we have studied the convergence of various moments of local density of states
and other physical quantities like Fermi energy and band energy. We have also
looked at the convergence of the magnetic moment of Ni, which is very sensitive
to numerical approximations towards the k-space value 0.6 with the
number of recursion steps prior to termination.Comment: Latex 2e, 21 Pages, 13 Figures, iopb style file attache
Study of the one dimensional Holstein model using the augmented space approach
A new formalism using the ideas of the augmented space recursion (introduced
by one of us) has been proposed to study the ground state properties of ordered
and disordered one-dimensional Holstein model. For ordered case our method
works equally well in all parametric regime and matches with the existing exact
diagonalization and DMRG results. On the other hand the quenched
substitutionally disordered model works in low and intermediate regime of
electron phonon coupling. Effect of phononic and substitutional disorder are
treated on equal footing.Comment: Accepted for publication in Physica