Showing papers by "Tanusri Saha-Dasgupta published in 2002"
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TL;DR: In this article, 3rd generation muffin-tin orbitals (MTOs) are shown to be able to be downfolded to smaller and smaller basis sets: sp^3d^10,sp^3, and bond orbitals.
Abstract: By the example of sp^3-bonded semiconductors, we illustrate what 3rd-generation muffin-tin orbitals (MTOs) are. We demonstrate that they can be downfolded to smaller and smaller basis sets: sp^3d^10,sp^3, and bond orbitals. For isolated bands, it is possible to generate Wannier functions a priori. Also for bands, which overlap other bands, Wannier-like MTOs can be generated a priori. Hence, MTOs have a unique capability for providing chemical understanding.
35 citations
TL;DR: In this article, an extended Hubbard model with first-principles tight-binding parameters has been used to investigate the nature of the insulating state driven by electronic correlations in the quarter-filled ladder compound α'NaV 2 O 5.
Abstract: The nature of the insulating state driven by electronic correlations in the quarter-filled ladder compound α'NaV 2 O 5 is investigated within a cluster dynamical mean-field approach. An extended Hubbard model with first-principles tight-binding parameters has been used. It is shown that the insulating state in the charge-disordered phase of this compound is formed due to the transfer of spectral density and dynamical charge fluctuations where for the latter, the role of intersite Coulomb interaction is found to be of crucial importance.
16 citations
TL;DR: In this paper, an ab initio study of the electronic structure of two isostructural quantum spin systems, KCuCl3 and TlCuCl3, which have recently attracted much attention due to their unconventional magnetic properties.
Abstract: We have performed an ab initio study of the electronic structure of two isostructural quantum spin systems, KCuCl3 and TlCuCl3, which have recently attracted much attention due to their unconventional magnetic properties. Our first-principles analysis shows unambiguously the role of Tl, as opposed to structural differences between the two compounds, in making TlCuCl3 a strongly coupled s = ½ dimer system compared to KCuCl3 which shows a weakly coupled s = ½ dimer behavior. Good agreement with the existing analysis of inelastic neutron scattering results has been observed.
10 citations
TL;DR: In this article, the electronic structure of two isostructural quantum spin systems, KCuCl$3}$ and TlCuCl$_{3}$, is studied. But the results of the analysis are limited.
Abstract: We have performed an {\it ab initio} study of the electronic structure of two isostructural quantum spin systems, KCuCl$_{3}$ and TlCuCl$_{3}$, which have recently attracted much attention due to their unconventional magnetic properties. Our first-principles analysis shows unambiguously the role of Tl, as opposed to structural differences between the two compounds, in making TlCuCl$_{3}$ a {\it strongly} coupled s=1/2 dimer system compared to KCuCl$_{3}$ which shows a {\it weakly} coupled s=1/2 dimer behavior. Good agreement with the existing analysis of inelastic neutron scattering results has been observed.
9 citations
Posted Content•
TL;DR: The optical properties of defect- Chalcopyrite type semiconductor ZnIn$_2$Te$_4$ have been studied by TB-LMTO first principle technique as discussed by the authors.
Abstract: Band structure and optical properties of defect- Chalcopyrite type semiconductor ZnIn$_2$Te$_4$ have been studied by TB-LMTO first principle technique. The optical absorption calculation suggest that ZnIn$_2$Te$_4$ is a direct-gap semiconductor having a band gap of 1.40 eV., which confirms the experimentally measured value. The calculated complex dielectric-function $\epsilon(E) = \epsilon_1(E) + i\epsilon_2(E)$ reveal distinct structures at energies of the critical points in the Brillouin zone.
5 citations