Lattice Dynamical Properties of Potassium

1981 ◽  
Vol 36 (11) ◽  
pp. 1242-1245
Author(s):  
O. P. Gupta
Keyword(s):  
Equilibrium Condition ◽  
Short Range ◽  
Phonon Dispersion ◽  
Waller Factor ◽  
Crystal Stability ◽  
Debye Waller Factor ◽  
Dynamical Properties ◽  
Experimental Values ◽  
Theoretical Results ◽  
Good Agreement

The phonon dispersion, temperature dependence of the Debye temperature, Debye-Waller factor, and Grüneisen parameter of potassium are calculated using a realistic lattice dynamical model. The model considers short range pairwise forces effective upto second neighbors and an improved electron ion interaction on the lines of Bhatia. An equilibrium condition, which preserves the crystal stability, is obtained. The theoretical results are found to be in good agreement with the experimental values.

Crystal Equilibrium and Lattice Dynamical Study of α-Iron and Chromium

1977 ◽  
Vol 32 (12) ◽  
pp. 1495-1502 ◽  
Author(s):  
O. P. Gupta ◽  
M. P. Hemkar
Keyword(s):  
Short Range ◽  
Phonon Dispersion ◽  
Mean Square Displacement ◽  
Waller Factor ◽  
Dynamical Study ◽  
Ion Interactions ◽  
Debye Waller Factor ◽  
Screening Parameter ◽  
The Mean ◽  
Ionic Lattice

Abstract Studies of the phonon dispersion, the temperature dependence of Debye-Waller factor, the Debye temperature, and the mean square displacement of α-iron and chromium have been made by means of a lattice dynamical model proposed by the authors. The model considers short range pairwise forces effective up to the second neighbours and electron-ion interactions on the lines of Bhatia using an appropriate value of the screening parameter. The volume force is aver­ aged over the whole Wigner-Seitz sphere. The ionic lattice is in equilibrium in a medium of electrons. The computed results compare well with experimental data.

Debye Waller Factors of fee Metals by the Modified Angular Force Model

1977 ◽  
Vol 32 (6) ◽  
pp. 570-576 ◽  
Author(s):  
Hira Lai Kharoo ◽  
O. P. Gupta ◽  
M. P. Hemkar
Keyword(s):  
Characteristic Temperature ◽  
Mean Square Displacement ◽  
Waller Factor ◽  
Force Model ◽  
Debye Waller Factor ◽  
Different Temperatures ◽  
Temperature Parameter ◽  
The Mean ◽  
Experimental Values ◽  
Theoretical Results

Abstract A modified form of the non-central force model which takes account of the electron-ion inter­ action term of the Kreb's model in the Clark, Gazis and Wallis type angular forces is considered to calculate the Debye-Waller exponents at different temperatures for five fee metals: copper, silver, gold, aluminium and nickel. The results are compared with the available x-ray measurements in terms of the temperature parameter Y of the Debye-Waller factor, the Debye characteristic temperature ΘM and the mean square displacement of the atoms. The theoretical results are found to be in reasonably satisfactory agreement with the experimental values.

scholarly journals Current Status and Developments of the Atomic Database on Rare-Earths at Mons University (DREAM)

Atoms ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 18 ◽  
Author(s):  
Pascal Quinet ◽  
Patrick Palmeri
Keyword(s):  
Rare Earths ◽  
Spectral Lines ◽  
Oscillator Strengths ◽  
Current Status ◽  
Time Resolved ◽  
Hartree Fock ◽  
Lanthanide Atoms ◽  
Experimental Values ◽  
Theoretical Results ◽  
Good Agreement

The main purpose of the Database on Rare Earths At Mons University (DREAM) is to provide the scientific community with updated spectroscopic parameters related to lanthanide atoms (Z = 57–71) in their lowest ionization stages. The radiative parameters (oscillator strengths and transitions probabilities) listed in the database have been obtained over the past 20 years by the Atomic Physics and Astrophysics group of Mons University, Belgium, thanks to a systematic and extensive use of the pseudo-relativistic Hartree-Fock (HFR) method modified for taking core-polarization and core-penetration effects into account. Most of these theoretical results have been validated by the good agreement obtained when comparing computed radiative lifetimes and accurate experimental values measured by the time-resolved laser-induced fluorescence technique. In the present paper, we report on the current status and developments of the database that gathers radiative parameters for more than 72,000 spectral lines in neutral, singly-, doubly-, and triply-ionized lanthanides.

scholarly journals MELTING OF THE VORTEX LATTICE IN LAYERED SUPERCONDUCTORS

2009 ◽  
Vol 23 (05) ◽  
pp. 661-672 ◽  
Author(s):  
BO FENG ◽  
ZHIGANG WU ◽  
DINGPING LI
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Vortex Lattice ◽  
Waller Factor ◽  
Layered Superconductor ◽  
Melting Line ◽  
Loop Order ◽  
Debye Waller Factor ◽  
Simulation And Experiment ◽  
Good Agreement

The structure function of the vortex lattice of layered superconductor is calculated to one-loop order. Based on a phenomenological melting criterion concerning the Debye–Waller factor, we calculate the melting line of the vortex lattice, and compare our results to Monte Carlo simulation and experiment. We find that our results are in good agreement with the Monte Carlo results. Moreover, our analytic calculation of the melting line of BSCCO fits the experiment reasonably.

scholarly journals Phonon Dispersion Relations for Chromium and Tantalum

1975 ◽  
Vol 28 (1) ◽  
pp. 57 ◽  
Author(s):  
Jyoti Prakash ◽  
LP Pathak ◽  
MP Hemkar
Keyword(s):  
Force Constant ◽  
Phonon Dispersion ◽  
Normal Modes ◽  
Inelastic Neutron ◽  
Neutron Spectroscopy ◽  
Phonon Dispersion Curves ◽  
Modes Of Vibration ◽  
Experimental Values ◽  
Good Agreement ◽  
Phonon Dispersion Relations

Phonon dispersion curves for the normal modes of vibration in chromium and tantalum are calculated along the symmetry directions [100], [110] and [111] using the five force-constant model of Behari and Tripathi (1970a). The results are compared with experimental values obtained from inelastic neutron spectroscopy and reasonably good agreement is found.

scholarly journals Transition spectral parameters of In-like Ba, La and Ce ions

2021 ◽  
Author(s):  
Miao Wu ◽  
Zhencen He
Keyword(s):  
Quantum Electrodynamics ◽  
Transition Probabilities ◽  
Energy Levels ◽  
Oscillator Strengths ◽  
Spectral Parameters ◽  
Hartree Fock ◽  
Experimental Values ◽  
Theoretical Results ◽  
Good Agreement ◽  
Line Strengths

The spectral parameters (energy levels, wavelengths, transition probabilities, line strengths and oscillator strengths) of resonance lines for Ba VIII, La IX and Ce X have been performed using the multiconfiguration Dirac-Hartree-Fock method, the contributions of quantum electrodynamics and Breit interactions correction are taken into considered. The calculated results of energy levels and wavelengths are in good agreement with experimental values and other calculation. The number of energy levels and wavelengths considered is larger than that of any other experiment values and other calculations. The transition probabilities, line strengths and oscillator strengths are also calculated where no other theoretical results and experimental values are available.

scholarly journals Electrostatically assisted macroion association

2021 ◽  
Vol 24 (3) ◽  
pp. 33502
Author(s):  
J. Reščiš
Keyword(s):  
Monte Carlo ◽  
Molecular Docking ◽  
Binding Energy ◽  
Short Range ◽  
Dynamic Equilibrium ◽  
Model System ◽  
Binding Energies ◽  
Effective Attraction ◽  
Theoretical Results ◽  
Good Agreement

A model system of highly asymmetric polyelectrolyte with directional short-range attractive interactions was studied by canonical Monte Carlo computer simulations. Comparison of MC data with previously published theoretical results shows good agreement. For moderate values of binding energies, which matches those of molecular docking, a dynamic equilibrium between free and dimerized macroions is observed. Fraction of dimerized macroions depends on macroion concentration, binding energy magnitude, and on the valency of small counterions. Divalent counterions induce an effective attraction between macroions and enhance dimerization. This effect is most notable at low to moderate macroion concentrations.

Investigation of some radiation interaction parameters for bacteria isolated from the soil in the low energy region

2020 ◽  
Vol 98 (3) ◽  
pp. 251-259
Author(s):  
F. Akman ◽  
B. Enez ◽  
S. Agüloğlu Fincan ◽  
F. Akdemir ◽  
I.H. Geçibesler
Keyword(s):  
Bacillus Subtilis ◽  
Effective Atomic Number ◽  
Mass Attenuation Coefficient ◽  
Geobacillus Stearothermophilus ◽  
Beam Geometry ◽  
Bacillus Simplex ◽  
Experimental Values ◽  
Attenuation Characteristics ◽  
Theoretical Results ◽  
Good Agreement

The purpose of this work, investigation of radiation attenuation characteristics, such as mass attenuation coefficient (μ/ρ), molar extinction coefficient (ε), effective atomic number (Zeff), and electron density (NE), of isolated bacteria from soil samples taken from Diyarbakır in Turkey. The experiments were performed using a narrow beam geometry with the help of the a high-resolution Si(Li) detector and three different radioactive sources at 15 different photon energies. The ε, Zeff, and NE values for some bacteria isolated from soil, such as Bacillus megaterium, Bacillus simplex, Bacillus subtilis, and commercially purchased Geobacillus stearothermophilus bacterium, were obtained from the measured μ/ρ results in the energy range from 13.94 to 88.04 keV. The experimental values were checked with two different theoretical results and good agreement was observed among them. The results show that Bacillus simplex bacterium has the highest values of μ/ρ and Zeff and Bacillus subtilis bacterium has the biggest values of ε and NE among the present bacteria.

Lattice dynamical study of face centred tetragonal indium

1983 ◽  
Vol 61 (1) ◽  
pp. 58-66 ◽  
Author(s):  
V. Ramamurthy ◽  
S. B. Rajendraprasad
Keyword(s):  
Frequency Distribution ◽  
Phonon Frequency ◽  
Phonon Dispersion ◽  
Dynamical Study ◽  
Atomic Interactions ◽  
Characteristic Features ◽  
Experimental Values ◽  
First Time ◽  
Good Agreement ◽  
Phonon Dispersion Relations

The phonon dispersion relations and the phonon frequency distribution function of fct indium have been deduced, for the first time, using a lattice dynamical model which expresses the atomic interactions in terms of central, angular, and volume forces. Six elastic constants, four zone boundary frequencies, and an equilibrium condition were used in the evaluation of the force constants. It is shown that this model is elastically consistent and conforms with the translational symmetry of the lattice; the phonon frequencies of indium deduced from it are in very good agreement with the experimental values of Reichardt and Smith and the theoretical values of Garrett and Swihart, but disagree with the theoretical values of Chulkov et al. as well as those of Gunton and Saunders at several wave vectors and polarizations. In addition the phonon frequency distribution curve obtained from this model is in overall agreement with those obtained from the electron tunnelling data, the inelastic scattering of neutrons as well as a pseudopotential model. The apparent characteristic features of these curves, the implications of the crystallographic equivalence between fct and bet lattices, and their relevance in the lattice dynamical study of indium are discussed.

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