Current Issue

Volume 55, No 3

June 2017

Visitors since 2010/06/28

Accepted paper

• Condensed Matter Physics
• Electronic Structure, Mechanical and Optical Properties of TiAl$_{3}$ (L1$_{2}$ \& D0$_{22}$) via First-Principles Calculations

(In Press, Uncorrected Proofs, PDF)

Altaf Hussain, Salman Mehmood, Nasir Rasool, Neng Li, and C. C. Dharmawardhana

Density functional theory based \textit{ab initio} calculations have been performed to study the electronic structure, mechanical and optical properties of L1$_{2}$ and D0$_{22}$ phases in TiAl$_{3}$ intermetallic alloy system. For electronic structures, bonding, and optical properties calculations we used orthogonalized linear combination of atomic orbitals (OLCAO) method, while for mechanical properties, Vienna \textit{ab initio} simulation package (VASP) is used. The band structure calculations show same number of bands crossing the Fermi level in both the L1$_{2}$ and D0$_{22}$ phases. Total density of states (TDOS) spectra reveal that the bottom of conduction band is dominated by Ti, while top of valence band being contributed mostly by Al atoms in both the phases. In D0$_{22}$ phase, DOS at the Fermi level $N(E_{F})$ are 5.51 while in L1$_{2}$ phase are 4.67 states/eV formula unit. Localization index calculations reveal that there exist highly localized states above the Fermi level. Results of elastic stiffness constants and bulk mechanical properties are in good agreement with the reported experimental data in literature for both the phases. Optical conductivity spectra in both the phases are rich in structures with the most prominent peak existing at 4.80 eV.

• Gravitation and Astrophysics
• Binding Energy in Self-gravitating Charged Plane Symmetric Systems

(In Press, Accepted Manuscripts, PDF)

M. Sharif and M. Zaeem Ul Haq Bhatti

This paper explores gravitational binding energy in static charged planar spacetime with perfect fluid configuration. We use Darmois formalism to explore the matching conditions of planar symmetry as an interior region and charged Vaidya as an exterior. The mass function is evaluated over the hypersurface to investigate the binding energy in the interior region. We conclude that gravitational field of the planar spacetime binds only the localized part while the non-localized part is due to the electric coupling.

• A Geometrization of Electric Charge and Mass by Means of a Solution to the Einstein and Maxwell Equations for Dust and a Radial Electric Field

(In Press, Accepted Manuscripts)

Yu. A. Khlestkov, L. A. Sukhanova, and N. S. Trushkin

It has been shown that a physical system consisting of a free electromagnetic field and electrically neutral dust-like matter can be completely geometrized in 4-space-time. This system can be represented as worlds with a non-trivial topology, connected through an infinite set of the non-closing non-stationary wormholes. The geometric image of the electric charge turns out to be the non-closing static throat. The internal world of the charged particle is discretized into disconnected regions of space-time, impenetrable to light trajectories. The electric charge $e$, rest mass $m_0$, and classical action of the gravitational field have a gravitational nature and are expressed in terms of the metric and the space-time curvature.

• Atomic, Molecular, and Optical Physics
• Landau Criterion in a Bose-Condensed Sodium Gas

(In Press, Accepted Manuscripts, PDF)

Abel Camacho Quintana

In light of the experimental evidence for the existence of a superfluidity region in a Bose--condensed sodium gas a theoretical model is put forward and with it the corresponding threshold velocity for the emergence of superfluidity is deduced. The prediction for the speed of sound and for the critical speed stemming from the present model will be compared against the extant experimental results. In addition, this prediction coincides also with previous calculations stemming from numerical simulations.

• Electric Dipole Transition Parameters for $2s3l3l'$- and $2p53l3l'$-$3l$ ($l, l'=0, 1, 2$) Transitions in W$^{63+}$

(In Press, Accepted Manuscripts, PDF)

Gülay G. Konan and Leyla Özdemir

Energy levels and electric dipole transition parameters such as wavelengths, transition probabilities and oscillator strengthsfrom the levels of $2s3l3l'$ and $2p53l3l'$ to $3l$, ($l, l’=0,1,2$), in highly ionized tungsten (W$^{63+}$, Na-like) have been reported. Highly ionized tungsten data are important, especially in the diagnostics of fusion energy devices and in astronomy. Calculations have been carried out from configuration interaction calculations using AUTOSTRUCTURE code (developed by Badnell) which includes Breit interactions and quantum electrodynamics contributions. The results obtained have been compared with other available works.

• Condensed Matter: Structure, etc.
• The Stable Orientations Analysis of Linearly Arrayed C$_{10}$H$_{16}$ Molecules in Single-Walled Carbon Nanotube by Using the Multiple-Molecule Model

(In Press, Accepted Manuscripts, PDF)

Z. Yao, C. J. Liu, Hang Lv, and B. B. Liu

A multiple-molecule model has firstly been constructed to study the stable orientations of encapsulated C$_{10}$H$_{16}$ molecules in single wall carbon nanotubes. The average molecular distance of adjacent C$_{10}$H$_{16}$ molecules is evaluated as 7.26 {\AA}. The orientational analysis show that tube's confinement effect plays a leading role for the diameter distribution from 9.5 {\AA} to 11.75 {\AA}, in which C$_{10}$H$_{16}$s exhibit optimal three- and two-fold axis orientations with the diameter smaller and larger than 11.3 {\AA}, respectively. Then H…H repulsive interaction of adjacent C$_{10}$H$_{16}$ molecules plays an important role with diameter increased to 12.13 {\AA}, which induces a slant two-fold orientation.

• Condensed Matter: Electronic Properties, etc.
• Impact of Channel Thickness on the Relocation of Valleys in Nano Silicon and Germanium DG-MOSFETs with Alternative Wafer Orientation

(In Press, Accepted Manuscripts, PDF)

Morteza Charmi

In this paper, a detailed simulation study of the channel thickness on the relocation valleys in double gate germanium and silicon MOSFETs with alternative wafer orientation is presented. Quantum simulation is performed based on self-consistent solutions of 2D Poisson's equation and Schrodinger equation with a generalized effective mass approach, within the non-equilibrium Green's function formalism. The effects channel thickness on the relocation of valleys are studied by focusing on the maximum subband potential, subband occupancy, subthreshold swing and on current for alternative wafer orientation. The results illustrate that the channel thickness supplants the valleys and their occupations that lead to different value of on current for every wafer orientation.