High Pressure Studies of Polyaromatic Molecilar Crystals: Optical and Electronic Properties from first Principles

2001 ◽  
Vol 665 ◽  
Author(s):  
Kerstom Weinmeier ◽  
Peter Puschning ◽  
Claudia Ambrosch-Drax ◽  
Georg Heimel ◽  
Egbert Zojer ◽  
...  
Keyword(s):  
First Principles ◽  
Intramolecular Interactions ◽  
Full Potential ◽  
Electrical And Optical Properties ◽  
Augmented Plane Wave ◽  
X Ray ◽  
Aromatic Molecules ◽  
High Pressure Studies ◽  
Optical And Electronic Properties ◽  
Linearized Augmented Plane Wave

Molecular crystals based on conjugated aromatic molecules have attracted a lot of interest, since their combined electrical and optical properties enable them many technical applicatins. The optical features and the anisotropic electron mobility strongly depend on the crystalline structure of such materials, which itself is determined by the inter-and intramolecular interactions. We investigate those interactions by performing full potential linearized augmented plane wave (FP-LAPW) band structure calculcations accompanied by X-ray [powder diffraction experiments imder hydrpstatoc [ressure up to 50 κbar. In this work we focus on the compounds anthracene and para-terphenyl and report their internal geometry, electronic structure and optical spectra as a functionof pressure.

X-ray photoemission spectroscopy of the 90 K superconductor Ba2YCu3O7−δ

1987 ◽  
Vol 2 (6) ◽  
pp. 768-774 ◽  
Author(s):  
Z. Iqbal ◽  
E. Leone ◽  
R. Chin ◽  
A. J. Signorelli ◽  
A. Bose ◽  
...  
Keyword(s):  
Core Level ◽  
Band Spectrum ◽  
Full Potential ◽  
Electronic Density ◽  
Augmented Plane Wave ◽  
X Ray ◽  
Superconducting Material ◽  
Auger Spectra ◽  
Linearized Augmented Plane Wave

The x-ray photoemission spectroscopie (XPS) data from different pelletized samples of the 90 K superconductor Ba2YCu3O7−δ (where δ∼0.2) have been obtained. The valence band spectrum (recorded at 300 and 170 K), which is composed of contributions from both the Cu 3d and O 2p levels, is compared with the full potential linearized augmented plane wave (FLAPW) calculated electronic density-of-states (DOS) reported by Massidda et al. and Mattheiss and Hamann. The experimental data indicate a relatively low DOS at the Fermi level. Detailed measurements of the core level Cu 2p, O 1s, Ba 3d, 4d, and Y 3d spectra of the superconducting and related standard materials, are presented. Data for the superconducting material were recorded in the freshly prepared form as well as after scraping in situ. The Cu 2p core level, satellite, and Auger spectra for the various samples were carefully examined in order to assess the possibility of the presence of Cu3+ ions in Ba2YCu3O7-δ. It is observed that surface reaction in air to form carbonates and hydroxides occurs readily in the superconducting material.

First-principles calculations of electronic and magnetic properties of XMn2Y2 (X = Ca, Sr; Y = Sb, Bi) compounds

2019 ◽  
Vol 33 (18) ◽  
pp. 1950199
Author(s):  
Zeshan Zada ◽  
A. Laref ◽  
G. Murtaza ◽  
Aurang Zeb ◽  
A. Yar
Keyword(s):  
Magnetic Properties ◽  
First Principles ◽  
Full Potential ◽  
First Principles Calculations ◽  
Generalized Gradient ◽  
Spin Configuration ◽  
Augmented Plane Wave ◽  
Electronic And Magnetic Properties ◽  
Magnetic Stability ◽  
Linearized Augmented Plane Wave

We have examined the magnetic stability; antiferromagnetic (AFM) ordering; electronic and magnetic properties of composition XMn2Y2 (X = Ca, Sr; Y = Sb, Bi) using framework of full-potential linearized augmented plane wave (FP-LAPW) method within generalized gradient (PBE-GGA) approximations in AFM phase. We have specified that AFM state is most suitable for these compounds as compared to other configurations at their relaxed lattice parameters. An AFM spin configuration of Mn atoms is shown to be impressive state for these compounds. Based on its electronic properties, these compounds have a metallic nature in Paramagnetic (PM) but in AFM phase it shows different nature from PM phase. From a suitable phase, it has been cleared that both Mn atoms well-adjusted antiferromagnetically.

First principles study of electronic and optical properties of InAs

Open Physics ◽  
2009 ◽  
Vol 7 (4) ◽  
Author(s):  
Zhenbao Feng ◽  
Haiquan Hu ◽  
Shouxin Cui ◽  
Wenjun Wang ◽  
Canyun Lu
Keyword(s):  
Optical Properties ◽  
First Principles ◽  
Optical Absorption Coefficient ◽  
Full Potential ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Augmented Plane Wave ◽  
Electronic And Optical Properties ◽  
Linearized Augmented Plane Wave ◽  
Good Agreement

AbstractThe electronic and optical properties of InAs in core-level spectra are calculated using the full-potential linearized augmented plane wave plus local orbitials (FP-LAPW +lo) method. The real and imaginary parts of the dielectric function ε(ω), the optical absorption coefficient I(ω), the reflectivity R(ω), the refractive index n(ω), and the extinction coefficient k(ω)are calculated. All these values are in good agreement with the experimental data. The effect of spin-orbit coupling on optical properties is also investigated and found to be quite small.

First-Principles Calculations and the Thermodynamics of Cementite

2010 ◽  
Vol 638-642 ◽  
pp. 3319-3324 ◽  
Author(s):  
Jae Hoon Jang ◽  
In Gee Kim ◽  
H.K.D.H. Bhadeshia
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Full Potential ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Augmented Plane Wave ◽  
Plane Wave Method ◽  
Lattice Constants ◽  
Unit Cells ◽  
Linearized Augmented Plane Wave

Thermodynamic data for the substitution of silicon and manganese in cementite have been estimated using first-principles methods in order to aid the design of steels where it is necessary to control the precipitation of this phase. The need for the calculations arises from the fact that for silicon the data cannot be measured experimentally; manganese is included in the analysis to allow a comparison with its known behaviour. The calculations for Fe3C, (Fe11Si4c)C4, (Fe11Si8d)C4, (Fe11Mn4c)C4 and (Fe11Mn8d)C4 are based on the total energy all-electron full-potential linearized augmented plane-wave method within the generalized gradient approximation to density functional theory. The output includes the ground state lattice constants, atomic positions and bulk moduli. It is found that (Fe11Si4c)C4 and (Fe11Si8d)C4 have about 52 and 37 kJ greater formation energy when compared with a mole of unit cells of pure cementite, whereas the corresponding energy for (Fe11Mn4c)C4 and (Fe11Mn8d)C4 is less by about 5 kJ mol1. These results for manganese match closely with published trends and data; a similar comparison is not possible for silicon but we correctly predict that the solubility in cementite should be minimal.

Structural and Electronic Properties of Narrow Gap Zincblende and Chalcopyrite Compounds

1990 ◽  
Vol 193 ◽  
Author(s):  
T.M. de Pascale ◽  
F. Meloni ◽  
M. Serra ◽  
S. Massidda ◽  
A. Continenza ◽  
...  
Keyword(s):  
Electronic Properties ◽  
First Principles ◽  
Full Potential ◽  
Narrow Gap ◽  
Augmented Plane Wave ◽  
Bulk Semiconductors ◽  
Structural And Electronic Properties ◽  
Indium Compounds ◽  
Linearized Augmented Plane Wave ◽  
Ternary Semiconductors

ABSTRACTIndium compounds and corresponding epitaxially grown superlattices have provided good single crystals suitable for accurate experimental measurements and have added new interest to the study of the constituent bulk semiconductors and the II-IV-V2 chalcopyrite crystal phases. This paper reports results of structural and electronic properties of narrow gap binary and ternary semiconductors determined selfconsistently from first principles using both the full potential linearized augmented plane wave (FLAPW) and norm-conserving pseudopotentials (PP) total-energy methods.

FIRST PRINCIPLES STUDY OF THE EFFECT OF ORBITAL-DEPENDENT EXCHANGE-CORRELATION POTENTIAL ON THE ELECTRONIC AND OPTICAL PROPERTIES OF Pb(Zr1-xTix)O3

2008 ◽  
Vol 22 (22) ◽  
pp. 2097-2103
Author(s):  
J. BAEDI ◽  
S. M. HOSSEINI ◽  
A. KOMPANY
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
First Principles ◽  
Full Potential ◽  
Electrical And Optical Properties ◽  
Augmented Plane Wave ◽  
Exchange Correlation ◽  
Exchange Correlation Potential ◽  
Correlation Potential ◽  
Perovskite Type

Ab initio calculations have been performed on the electrical and optical properties of Pb ( Zr 1-x Ti x) O 3 ceramics with x = 0.5, which is a perovskite type compound. The Kohn–Sham equations were solved using the full potential linear Augmented Plane Wave approach (FP-LAPW). We used GGA, LDA + U and GGA + U approximations for the exchange correlation potential. The results show that with a proper choice of U eff = U - J, for any atoms of the compound, the theoretical values of band gap and the refractive index have been improved compared to their experimented values.

First-Principles Calculations of Electronic Structure and Structural Properties for MoV, MoNb, and MoTa

2000 ◽  
Vol 646 ◽  
Author(s):  
R. de Coss ◽  
A. Aguayo ◽  
G. Murrieta
Keyword(s):  
Electronic Structure ◽  
Melting Point ◽  
Bulk Modulus ◽  
First Principles ◽  
Electronic Structure Calculations ◽  
Full Potential ◽  
First Principles Calculations ◽  
Augmented Plane Wave ◽  
Linearized Augmented Plane Wave ◽  
Structure Calculations

ABSTRACTFirst-principles total-energy electronic structure calculations based on the full-potential linearized augmented plane wave (LAPW) method have been used to study the electronic and elastic properties of MoV, MoNb, and MoTa with the B2 (CsCl) estructure. From the calculated values for the bulk modulus we have determined the melting temperature using an empirical correlation. The chemical bond and the electronic structure around the Fermi level are analyzed. In particular, we found that MoTa which have the experimental determined highest melting point of the studied materials, present the largest bulk modulus and the highest degree of covalence bonding of these intermetallic compounds.

scholarly journals SOFT X-RAY ABSORPTION SPECTROSCOPY OF THE MgB2 BORON K EDGE IN AN MgB2/Mg COMPOSITE

2006 ◽  
Vol 20 (19) ◽  
pp. 1207-1216 ◽  
Author(s):  
D. A. FISCHER ◽  
A. R. MOODENBAUGH ◽  
QIANG LI ◽  
G. D. GU ◽  
YIMEI ZHU ◽  
...  
Keyword(s):  
Absorption Spectroscopy ◽  
Sample Surface ◽  
Fluorescence Yield ◽  
Full Potential ◽  
Augmented Plane Wave ◽  
X Ray ◽  
Plane Wave Method ◽  
Edge Spectrum ◽  
Linearized Augmented Plane Wave ◽  
X Ray Absorption

Soft X-ray absorption spectroscopy (XAS), using fluorescence yield, was used to study the boron K near edge in MgB 2 superconductor. The sample consists of MgB 2 crystallites randomly oriented in a magnesium matrix. Abrasion of the sample surface in vacuum provides a surface relatively free of boron-containing impurities. The intrinsic boron K near edge spectrum of the sample at a temperature of 295 K is identified. This spectrum is then compared in detail with a spectrum calculated using the full potential linearized augmented plane wave method. Features predicted by the theory appear near the expected energies, with qualitative agreement regarding shape and intensity.

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