Showing papers by "Tanusri Saha-Dasgupta published in 2004"

TiOCl, an orbital-ordered system?

Abstract: We present first-principles density-functional calculations and downfolding studies of the electronic and magnetic properties of the layered quantum spin system TiOCl. We discuss explicitly the nature of the exchange paths and the concept of orbital ordering in this material. An analysis of the electronic structure of slightly distorted structures according to various phonon modes allowed in this material suggests that this system may be subject to orbital fluctuations driven by the electron-phonon coupling.

Electronic and optical properties of ZnIn2Te4

Abstract: Band structure and optical properties of defect-chalcopyrite-type semiconductor ZnIn2Te4 have been studied by TB-LMTO first-principle technique. The band structure calculation suggests that ZnIn2Te4 is a direct-gap semiconductor having a band gap of 1.37 eV ., which is very close to the experimentally measured value, 1.40 eV . The calculated optical response functions confirm the experimentally measured values.

Symmetry reduction in the augmented space recursion formalism for random binary alloys

Abstract: We present here an efficient method which systematically reduces the rank of the augmented space and thereby helps to implement augmented space recursion for any real calculation. Our method is based on the symmetry of the Hamiltonian in the augmented space and keeping recursion basis vectors in the irreducible subspace of the Hilbert space.