Unpaired forces in the study of lattice dynamics of thorium

1979 ◽  
Vol 57 (11) ◽  
pp. 1838-1842 ◽  
Author(s):  
K. N. Awasthi ◽  
S. S. Kushwaha
Keyword(s):  
Experimental Data ◽  
Phenomenological Model ◽  
Lattice Dynamics ◽  
Phonon Dispersion ◽  
Body Rotation ◽  
Symmetry Requirement ◽  
Screened Coulomb Potential ◽  
Three Body ◽  
Good Agreement ◽  
Phonon Dispersion Relations

A phenomenological model that considers interaction between ions in terms of two-body (central) and three-body (unpaired) forces and evaluates the effect of electron–ion interaction through a screened coulomb potential is developed for studying the lattice dynamics of thorium. The model satisfies the symmetry requirement of a lattice and fulfils the condition of invariance under rigid body rotation. Computed phonon dispersion relations and (θD – T) curve for thorium are in reasonably good agreement with the corresponding experimental data.

Lattice Properties of Ge and GaAs Strained-Layers on Si

1994 ◽  
Vol 356 ◽  
Author(s):  
Resul Eryigit ◽  
Zhifeng Sui ◽  
Irving P. Herman
Keyword(s):  
Experimental Data ◽  
Thin Films ◽  
Lattice Dynamics ◽  
Phonon Dispersion ◽  
Group Iv ◽  
Dynamics Model ◽  
Strained Layers ◽  
Quasiharmonic Approximation ◽  
Semiconductor Thin Films ◽  
Phonon Dispersion Relations

AbstractA phenomenological lattice dynamics model has been developed that describes how strain affects phonon frequencies and elastic constants in Group IV and III-V semiconductor thin films and strained layers. Using this model, the phonon dispersion relations for strained-layer heterostructures of Ge and GaAs on Si have been obtained in the quasiharmonic approximation. This model uses available experimental data and can predict the effect of arbitrary strains on thin films.

Resonant and non-resonant contributions of B → K∗(p1,𝜖1){Kπ,ππ,KK} decay modes

2019 ◽  
Vol 34 (06) ◽  
pp. 1950043
Author(s):  
Mahboobeh Sayahi
Keyword(s):  
Experimental Data ◽  
Perturbation Theory ◽  
Chiral Perturbation Theory ◽  
Branching Ratio ◽  
Heavy Meson ◽  
Chiral Perturbation ◽  
Decay Modes ◽  
Qcd Factorization ◽  
Three Body ◽  
Good Agreement

In this paper, the non-leptonic three-body decays [Formula: see text], [Formula: see text], [Formula: see text] are studied by introducing two-meson distribution amplitude for the [Formula: see text], [Formula: see text] and [Formula: see text] pairs in naive and QCD factorization (QCDF) approaches, such that the analysis is simplified into quasi-two body decays. By considering that the vector meson is being ejected in factorization, the resonant and non-resonant contributions are analyzed by using intermediate mesons in Breit–Wigner resonance formalism and the heavy meson chiral perturbation theory (HMChPT), respectively. The calculated values of the resonant and non-resonant branching ratio of [Formula: see text], [Formula: see text] and [Formula: see text] decay modes are compared with the experimental data. For [Formula: see text] and [Formula: see text], the non-resonant contributions are about 70–80% of experimental data, for which the total results by considering resonant contributions are in good agreement with the experiment.

Lattice dynamics of xenotime: The phonon dispersion relations and density of states ofLuPO4

1997 ◽  
Vol 56 (18) ◽  
pp. 11584-11592 ◽  
Author(s):  
J. C. Nipko ◽  
C.-K. Loong ◽  
M. Loewenhaupt ◽  
M. Braden ◽  
W. Reichardt ◽  
...  
Keyword(s):  
Density Of States ◽  
Lattice Dynamics ◽  
Phonon Dispersion ◽  
Dispersion Relations ◽  
Phonon Dispersion Relations

scholarly journals Lattice Dynamics of the High Tc Superconductor ErBa2Cu3O7

1994 ◽  
Vol 47 (1) ◽  
pp. 103 ◽  
Author(s):  
S Mohan ◽  
R Kannan
Keyword(s):  
Lattice Dynamics ◽  
Many Body ◽  
New Approach ◽  
High Tc ◽  
High Tc Superconductor ◽  
Zone Centre ◽  
Three Body ◽  
Many Body Interactions ◽  
Good Agreement ◽  
Infrared Data

The lattice dynamics of the high Tc superconductor ErBa2Cu307 have been investigated in detail with a modified three-body force shell model. The model accounts for the effect of many-body interactions in the lattice potential. The aim of the present work is to treat the various interactions between the ions in generalised way without making them numerically equal. The values of the phonon frequencies calculated at the zone centre by this new approach are in good agreement with the available Raman and infrared data.

scholarly journals Lattice dynamics in CePd2Al2 and LaPd2Al2

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Petr Doležal ◽  
Petr Cejpek ◽  
Satoshi Tsutsui ◽  
Koji Kaneko ◽  
Dominik Legut ◽  
...  
Keyword(s):  
Lattice Dynamics ◽  
Phonon Dispersion ◽  
Elastic Interaction ◽  
Bound State ◽  
Dispersion Curves ◽  
Phonon Modes ◽  
Phonon Dispersion Curves ◽  
X Ray Scattering ◽  
Oppenheimer Approximation ◽  
Good Agreement

AbstractThe interaction between phonons and 4f electrons, which is forming a new quantum state (quasi-bound state) beyond Born-Oppenheimer approximation, is very prominent and lattice dynamics plays here a key role. There is only a small number of compounds in which the experimental observation suggest such a scenario. One of these compounds is CePd2Al2. Here the study of phonon dispersion curves of (Ce,La)Pd2Al2 at 1.5, 7.5, 80 and 300 K is presented. The inelastic X-ray scattering technique was used for mapping the phonon modes at X and Z points as well as in Λ and Δ directions, where the symmetry analysis of phonon modes was performed. The measured spectra are compared with the theoretical calculation, showing very good agreement. The measurements were performed in several Brillouin zones allowing the reconstruction of phonon dispersion curves. The results are discussed with respect to the magneto-elastic interaction and are compared with other cerium compounds. The phonon mode symmetry A1g was found to be unaffected by the interaction, which is in contrast to previous assumptions.

Lattice dynamics of ZnTe, CdTe, GaP, and InP

1980 ◽  
Vol 58 (3) ◽  
pp. 351-358 ◽  
Author(s):  
M. S. Kushwaha ◽  
S. S. Kushwaha
Keyword(s):  
Lattice Dynamics ◽  
Present Model ◽  
Phonon Dispersion ◽  
Model Parameters ◽  
Force Model ◽  
Phonon Dispersion Curves ◽  
Bending Force ◽  
Zinc Blende ◽  
Bond Bending ◽  
Good Agreement

An eight-parameter bond-bending force model (BBFM), recently developed by us for zinc-blende (ZB) structure, has been used to study the lattice dynamics of other compounds of the II–VI and III–V groups. The model parameters were calculated using six critical point phonon frequencies, two elastic constants, and the lattice equilibrium condition. Phonon dispersion curves, phonon density of states, and Debye-characteristic temperatures have been calculated. The comparison of theoretical and the available experimental results reveals a fairly good agreement. The merits and demerits of the present model have been discussed in full.

LATTICE DYNAMICS OF α-LiIO3

1991 ◽  
Vol 05 (17) ◽  
pp. 1167-1173
Author(s):  
YIMIN JIANG ◽  
HONG LIN ◽  
CHENG GOU ◽  
SHIWEN NIU
Keyword(s):  
Lattice Dynamics ◽  
Molecular Crystal ◽  
Field Model ◽  
Phonon Dispersion ◽  
Normal Modes ◽  
Coulomb Force ◽  
Strong Mixing ◽  
Phonon Dispersion Curves ◽  
Good Agreement ◽  
Rigid Ion Model

The phonon dispersion curves of α- LiIO 3, which exhibit a characteristic molecular crystal behaviour, are calculated on the basis of a modified rigid-ion model in which a Born-Mayer potential is used for short-range repulsive interactions between Li ions and [Formula: see text] groups and a central force constant model is used for internal interactions in the [Formula: see text] group. The computed phonon frequencies are in good agreement with those of Raman, infrared and neutron measurements. The calculations show a strong mixing of the pre-normal modes given by Crettez et al.,4 therefore indicating that the long-range Coulomb force may change greatly the assignments previously obtained from a force-field model.

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 Study of lattice dynamics of silicon

BIBECHANA ◽  
2012 ◽  
Vol 9 ◽  
pp. 13-17
Author(s):  
SRB Thapa
Keyword(s):  
Lattice Dynamics ◽  
Phonon Dispersion ◽  
Characteristic Temperature ◽  
Central Force ◽  
Phonon Dispersion Curves ◽  
Valence Force Field ◽  
Model Following ◽  
Bond Stretching ◽  
Bond Bending ◽  
Good Agreement

Lattice dynamics of Si has been investigated by using a Urey-Bradley Valence Force Field (UVFF) model which is a phenomenological model. In this model following interactions are taken into account: (i) the central force due to bond-stretching (ii) the angular force due to bond bending (iii) central force between non-bonded atoms (iv) the force due to interaction of one internal co-ordinate to adjacent internal coordinate. Calculated results of phonon dispersion curves, Debye Characteristic temperature, microscopic elastic constants and Bulk modulus of Si are compared with experimental results giving fairly good agreement. DOI: http://dx.doi.org/10.3126/bibechana.v9i0.7145BIBECHANA 9 (2013) 13-17

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