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FP-LAPW investigation of mechanical and thermodynamic properties of Na2X (X = S and Se) under pressure and temperature effects

Bidai K., Ameri M., Bensaid D, Moulay N. E., Al-Douri Y., Ameri I.

Materials Science Poland

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2015

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Vol. 33, No. 3

649--659

EN

Structural, elastic and thermodynamic properties of sodium chalcogenides (Na2X, X = S, Se) have been calculated using FP-APW+lo method. The ground state lattice parameter, bulk moduli have been obtained. The Zener anisotropy factor, Poisson’s ratio, shear modulus, Young’s modulus, have also been calculated. The calculated structural and elastic constants are in good agreement with the available data. We also determined the thermodynamic properties, such as heat capacities Cv and Cp, thermal expansion α, entropy S, and Debye temperature ΘD, at various pressures and temperatures for Na2X compounds. The elastic constants under high pressure and temperature are also calculated and elaborated.

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First-principles study of electronic and optical properties of cubic perovskite CsSrF3

Ephraim Babu K., Veeraiah A., Tirupathi Swamy D., Veeraiah V.

Materials Science Poland

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2012

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Vol. 30, No. 4

359--367

EN

We present first principles calculations of the electronic, structural and optical properties of the cubic perovskite CsSrF3 by using the full potential linearized augmented plane wave (FP-LAPW) plus local orbitals method with generalized gradient approximation (GGA) in the frame work of density functional theory. The calculated lattice constant is in a good agreement with the experimental result. The electronic band structure shows that the fundamental band gap is wide and direct at G point. The contribution of the different bands was analyzed from the total and partial density of states curves. The charge density plots show strong ionic bonding in Cs-F, ionic and weak covalent bonding between Sr and F. The calculated optical spectra viz., the dielectric function, optical refiectivity, absorption coefficient, real part of optical conductivity, refractive index, extinction coefficient and electron energy loss, are presented for the energy range of 0-30 eV.

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Wpływ lokalnego nieporządku na strukturę elektronową i własności topologiczne gęstości elektronowej w roztworach stałych AgXSe2 (X = Sb,Sn)

Koleżyński A., Wojciechowski K.

Materiały Ceramiczne

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2011

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T. 63, nr 4

736-742

PL

W pracy opisano rezultaty badań teoretycznych struktury elektronowej - wykonanych w oparciu o wyniki obliczeń ab initio, przeprowadzonych za pomocą programu WIEN2k (metoda DFT FP-LAPW stowarzyszonych fal płaskich w pełnym potencjale krystalicznym w ramach formalizmu teorii funkcjonału gęstości) - oraz topologii gęstości elektronowej (w oparciu o formalizm QTAiM kwantowej teorii atomów w cząsteczkach R.F.W. Badera) dla wybranych modelowych roztworów stałych Ag(SbxSn1-x)Se2. Otrzymane wyniki poddane zostały szczegółowej analizie w kontekście wpływu obniżenia lokalnej symetrii i stopnia domieszkowania cyną na kształt i własności struktury elektronowej i topologicznych własności gęstości elektronowej w punktach krytycznych wiązań.

EN

The results of theoretical studies of electronic structure, obtained by means of the full-potential linearized augmented plane wave method within DFT formalism as implemented in Wien2k package, and electron density topology and bonding, obtained by means of the Bader’s quantum theory of atoms in molecules topological analysis of total electron density derived from FP-LAPW calculations, were carried out f orchosen solid solutions of Ag(SbxSn1-x)Se2 and described in the paper. Detailed analysis of the obtained results from the point of view of the dependence of electronic structure and topological properties of bond critical points on local ordering and level of tin doping is presented.

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Ab initio study of the effect of pressure on the hyperfine parameters of 57Fe in bcc phase

Michalecki T., Deniszczyk J., Frąckowiak J.

Nukleonika

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2003

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Vol. 48,suppl.1

45-48

EN

In this paper the results of studies on the effect of pressure on hyperfine magnetic field (Bf) and isomer shift (IS) for Fe-bcc are presented. Two calculation methods were used: TB-LMTO (Tight Binding Linear Muffin-Tin) and FP-LAPW (Full Potential Linearized Augmented Plane Wave) and the obtained results have been compared. Both methods lead to comparable results. In the study a particular emphasis has been laid on investigations of the atomic core electrons (1s, 2s, 3s) and of the conduction electrons 4s on the Bf and IS values. The calculated values of the dIS/dlnV and dlnB /dlnV parameters give evidence of good conformity with those derived from experimental data.