Lattice dynamics of thallium iodide

1988 ◽  
Vol 66 (7) ◽  
pp. 630-632 ◽  
Author(s):  
C. Haridass ◽  
R. Sundararajan ◽  
N. Krishnamurthy
Keyword(s):  
Crystal Structure ◽  
Shell Model ◽  
Satisfactory Agreement ◽  
Lattice Dynamics ◽  
Optical Phonons ◽  
Long Wavelength ◽  
Potential Parameters

The long-wavelength optical phonons in orthorhombic TlI are calculated employing a shell model and transferring the potential parameters from cubic TlI and TlBr. Satisfactory agreement between experimental Raman and infrared phonons suggests that the change in the crystal structure alone is the main reason for the redistribution of phonons in the cubic to orthorhombic transition.

Effect of screening on the long-wavelength optical phonons in La1.85Sr0.15CuO4

1992 ◽  
Vol 70 (5) ◽  
pp. 352-356
Author(s):  
Chellam Ramakrishnan ◽  
K. Navaneethakrishnan ◽  
N. Krishnamurthy
Keyword(s):  
Coulomb Potential ◽  
Lattice Dynamics ◽  
Wavelength Region ◽  
Coulomb Field ◽  
Longitudinal Optical ◽  
Charge Carriers ◽  
Optical Phonons ◽  
Coupling Coefficients ◽  
Long Wavelength ◽  
Rigid Ion Model

The lattice dynamics of La1.85Sr0.15CuO4 are studied with a rigid-ion model that takes into account the anisotropic screening of the Coulomb field by the charge carriers. The coupling coefficients for the screened potential are obtained using a generalized Ewald transformation that incorporates the Thomas–Fermi screening function. From the calculated phonons in the long-wavelength region it can be seen that the screening considerably reduces the longitudinal optical–transverse optical splitting of the polar modes. The nonpolar modes do not exhibit any changes in their behaviour with respect to that in the unscreened Coulomb potential.

Crystal structure and lattice dynamics of hydrogen-loaded austenitic steel

2003 ◽  
Vol 112 ◽  
pp. 407-410
Author(s):  
S. A. Danilkin ◽  
M. Hölzel ◽  
H. Fuess ◽  
H. Wipf ◽  
T. J. Udovic ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Austenitic Steel ◽  
Lattice Dynamics

scholarly journals Lattice Dynamics of Simple Harmonic and Anharmonic Shell Models

1967 ◽  
Vol 20 (5) ◽  
pp. 495 ◽  
Author(s):  
J Oitmaa
Keyword(s):  
Dipole Moment ◽  
Shell Model ◽  
Lattice Dynamics ◽  
Higher Order ◽  
Force Constants ◽  
Dynamical Equations ◽  
Normal Coordinates ◽  
Shell Models ◽  
Rigid Ion Model ◽  
Explicit Expressions

The lattice dynamics of harmonic and anharmonic shell models are reviewed. It is shown that the various dynamical equations for the shell model can be expressed in the same form as those for the rigid ion model, but with modified force constants. The anharmonic shell model leads to higher order contributions to the dipole moment, quadratic and cubic in the normal coordinates, for which explicit expressions are obtained.

Lattice dynamics study on cubic barium titanate based upon a modified rigid-shell model

1998 ◽  
Vol 206 (1) ◽  
pp. 219-230
Author(s):  
N. Takesue ◽  
H. Kubo ◽  
Haydn Chen
Keyword(s):  
Barium Titanate ◽  
Shell Model ◽  
Lattice Dynamics ◽  
Rigid Shell

Long wavelength optical phonons in mixed crystals

1971 ◽  
Vol 20 (85) ◽  
pp. 359-404 ◽  
Author(s):  
I.F. Chang ◽  
S.S. Mitra
Keyword(s):  
Mixed Crystals ◽  
Optical Phonons ◽  
Long Wavelength

Temperature evolution of pentacene crystal structure and phonon dynamics

2002 ◽  
Vol 725 ◽  
Author(s):  
Matteo Masino ◽  
Alberto Girlando ◽  
Raffaele G. Della Valle ◽  
Elisabetta Venuti ◽  
Luca Farina ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Thermal Expansion ◽  
Lattice Dynamics ◽  
Low Frequency ◽  
Minimum Potential Energy ◽  
X Ray ◽  
Phonon Dynamics ◽  
Minimum Potential ◽  
Effects Of Temperature ◽  
Experimental Raman Spectrum

AbstractWe investigate the relationships among all currently known X-ray structures of crystalline pentacene by calculating their “inherent” structures of minimum potential energy. We are thus able to show that two distinct bulk crystalline phases of pentacene exist, with very subtle but clear di.erences. We then assess the effects of temperature on the crystal structures, by including both inter- molecular and low-frequency intra-molecular phonons in the framework of quasi harmonic lattice dynamics methods. In this way we properly reproduce the experimental thermal expansion, and obtain a reliable description of the phonon dynamics and of its temperature dependence. The calculated phonon frequencies compare well with the experimental Raman spectrum.

Crystal structure and lattice dynamics of chromium hydrides

2007 ◽  
Vol 430 (1-2) ◽  
pp. 22-28 ◽  
Author(s):  
V.E. Antonov ◽  
A.I. Beskrovnyy ◽  
V.K. Fedotov ◽  
A.S. Ivanov ◽  
S.S. Khasanov ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Lattice Dynamics

Long-wavelength optical phonons inZn1−xMnxSe

1989 ◽  
Vol 39 (2) ◽  
pp. 1207-1211 ◽  
Author(s):  
W. Lu ◽  
P. L. Liu ◽  
G. L. Shi ◽  
S. C. Shen ◽  
W. Giriat
Keyword(s):  
Optical Phonons ◽  
Long Wavelength

Anisotropy of long-wavelength optical phonons in GaAs/AlAs superlattices

JETP Letters ◽  
2014 ◽  
Vol 99 (7) ◽  
pp. 396-399 ◽  
Author(s):  
V. A. Volodin ◽  
M. P. Sinyukov
Keyword(s):  
Optical Phonons ◽  
Long Wavelength
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