The effects on the lattice dynamical properties of the temperature and pressure in random NiPd alloy

2013 ◽  
Vol 91 (10) ◽  
pp. 833-838 ◽  
Author(s):  
S. Kazanc
Keyword(s):  
Phonon Dispersion ◽  
Alloy System ◽  
External Pressure ◽  
Dynamics Simulation ◽  
Dynamical Matrix ◽  
High Symmetry ◽  
Embedded Atom ◽  
Dynamical Properties ◽  
Temperature And Pressure ◽  
Many Body Interactions

In this work, the effects on the lattice dynamical properties, such as phonon dispersion, second order elastic constants, and bulk modulus of the temperature and pressure in random NiPd binary alloy system was investigated using molecular dynamics simulation. The interactions between atoms were modelled using the Sutton–Chen-type embedded atom method based on many-body interactions. The phonon frequencies were calculated from the dynamical matrix for [100], [110], and [111] high symmetry directions of the Brillouin zone. The obtained results show that the external pressure cause an increment in phonon frequencies, and the increase of temperature causes a decrease in longitudinal and transverse acoustic phonon frequencies because of thermal expansion.

scholarly journals Ab-initio density-functional lattice-dynamics studies of ice

2003 ◽  
Vol 81 (1-2) ◽  
pp. 115-122 ◽  
Author(s):  
A S Cote ◽  
I Morrison ◽  
X Cui ◽  
S Jenkins ◽  
D K Ross
Keyword(s):  
Ab Initio ◽  
Force Constant ◽  
Density Functional ◽  
Phonon Dispersion ◽  
Scattering Data ◽  
Full Potential ◽  
Dynamical Matrix ◽  
Constant Matrix ◽  
Force Constant Matrix ◽  
Dynamical Properties

We present the results of first-principles computational studies of the dynamical properties of hexagonal ice using both the ab-initio pseudopotential method and the full-potential augmented plane-wave method. Properties obtained using both the generalized gradient approximation (GGA) and the meta-GGA in density-functional theory are compared. The lattice-dynamical properties of the structures are obtained using a finite-difference evaluation of the dynamical matrix and force-constant matrix from atomic forces. Phonon dispersion is evaluated by the direct determination of the force-constant matrix in supercells derived from the primitive molecule unit cells with the assumption that force constants are zero beyond the second molecular nearest neighbors. The k-dependent phonon frequencies are then obtained from the force-constant matrix and dispersion relations, and the Brillouin-zone integrated density of states is evaluated. The importance of phonon dispersion in the various regions of the phonon spectra is then assessed and compared to existing neutron-scattering data. Frozen-phonon calculations are used to compare phonon frequencies evaluated in both the GGA and meta-GGA. PACS Nos.: 61.12Ex, 63.20Dj

CALCULATION OF PHONON DISPERSION FOR TRANSITION METALS V, Nb AND Ta

2011 ◽  
Vol 25 (29) ◽  
pp. 4047-4053 ◽  
Author(s):  
YOU XIE ◽  
JIAN-MIN ZHANG
Keyword(s):  
Transition Metals ◽  
Lattice Dynamics ◽  
Phonon Frequency ◽  
Phonon Dispersion ◽  
Atomic Mass ◽  
The Other ◽  
Embedded Atom Method ◽  
High Symmetry ◽  
Embedded Atom ◽  
Good Agreement

Combining the modified analytic embedded atom method (MAEAM) with lattice dynamics theory, the phonon dispersion along five symmetry directions have been calculated for three transition metals V, Nb and Ta . A good agreement between calculations and experiments along three high symmetry directions [q00], [qqq] and [qq0] implies that the predicted phonon dispersion along the other two directions [1qq] and [Formula: see text] are well behaved. Along each direction, the phonon frequency decreases for V, Nb and Ta successively may be related to the ratio of the cohesive energy to atomic mass.

Elastic and Lattice Dynamical Properties of Metals Studied by N-Body Potential

1994 ◽  
Vol 367 ◽  
Author(s):  
Yoshiaki Kogure ◽  
O. Kouchi ◽  
M. Doyama
Keyword(s):  
Dispersion Relation ◽  
Elastic Constants ◽  
Phonon Dispersion ◽  
Embedded Atom Method ◽  
Third Order ◽  
Phonon Dispersion Relation ◽  
Embedded Atom ◽  
Third Order Elastic Constants ◽  
Dynamical Properties ◽  
Body Potential

AbstractHigher order elastic constants and phonon dispersion relation have been calculated by using the n-body potential based on the embedded atom method. Results of second- and third-order elastic constants for Cu, Ag, and Au crystal were compared with the experimental data and the Cauchy discrepancy was discussed. A result of phonon dispersion relation for Cu crystal was also shown.

Classical Molecular Dynamics Simulation of Structural and Dynamical Properties of II-VI and III-V Semiconductors

2006 ◽  
Vol 258-260 ◽  
pp. 522-530 ◽  
Author(s):  
José Pedro Rino ◽  
Paulo S. Branício ◽  
Denílson S. Borges
Keyword(s):  
Interaction Potential ◽  
Dipole Interaction ◽  
Van Der Waals Interactions ◽  
Dynamics Simulation ◽  
Static Structure Factor ◽  
Static Structure ◽  
Liquid Phases ◽  
Bond Stretching ◽  
Dynamical Properties ◽  
Three Body

An effective inter-atomic potential is proposed in order to describe structural and dynamical properties of II-VI and III-V semiconductors. The interaction potential consists of twoand three-body interactions. The two-body term takes into account steric repulsion, charge-induce dipole interaction due to the electronic polarizability of ions, Coulomb interaction due to charge transfer between ions, and dipole-dipole (van der Waals) interactions. The three-body term, which has a modified Stillinger-Weber form, describes bond-bending as well as bond-stretching effects. Here we report the fitting and the application of this interaction potential for InP in the crystalline phase and for CdTe in the crystalline and liquid phases. The structural correlations are discussed through pair distribution, coordination number and bond-angle functions. Vibrational density of states for InP and CdTe as well as the static structure factor for liquid CdTe are in very good agreement with experimental data.

Simulation of Stress Distribution and Mechanical Response of Metallic Glasses

1998 ◽  
Vol 554 ◽  
Author(s):  
Y. Kogure ◽  
M. Doyama
Keyword(s):  
Stress Distribution ◽  
Metallic Glasses ◽  
Mechanical Response ◽  
Local Density ◽  
Glassy State ◽  
Dynamics Simulation ◽  
Single Atom ◽  
Atomic Interaction ◽  
Embedded Atom ◽  
Embedded Atom Method Potential

AbstractMolecular dynamics simulation of the metallic glasses has been done. The embedded atom method potential function for copper is used to express the atomic interaction. The stress distribution in the glassy state is evaluated from specific volume occupied by single atom and local density in divided cells. The displacements of individual atom under the shear stress are calculated and the correlation between the displacements and the atomic volumes are investigated.

Dislocation Generation and Crack Propagation in Metals Examined in Molecular Dynamics Simulations

1992 ◽  
Vol 278 ◽  
Author(s):  
J. A. Rifkin ◽  
C. S. Becquart ◽  
D. Kim ◽  
P. C. Clapp
Keyword(s):  
Crack Propagation ◽  
Atomistic Simulations ◽  
Many Body ◽  
Dislocation Generation ◽  
Embedded Atom ◽  
Stress Levels ◽  
Different Temperatures ◽  
The Many ◽  
Dynamics Simulations ◽  
Many Body Interactions

AbstractWe have carried out a series of atomistic simulations on arrays of about 10,000 atoms containing an atomically sharp crack and subjected to increasing stress levels. The ordered stoichiometric alloys B2 NiAl, B2 RuAl and A15 Nb3AI have been studied at different temperatures and stress levels, as well as the elements Al, Ni, Nb and Ru. The many body interactions used in the simulations were derived semi-empirically, using techniques related to the Embedded Atom Method. Trends in dislocation generation rates and crack propagation modes will be discussed and compared to experimental indications where possible, and some of the simulations will be demonstrated in the form of computer movies.

Self-diffusion of lignite/water under different temperatures and pressure: A molecular dynamics study

2016 ◽  
Vol 30 (01) ◽  
pp. 1550253 ◽  
Author(s):  
Xinjian Liu ◽  
Yu Jin ◽  
Congliang Huang ◽  
Jingfeng He ◽  
Zhonghao Rao ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Water System ◽  
Simulation Method ◽  
The Self ◽  
Dynamics Simulation ◽  
Low Rank ◽  
Self Diffusion ◽  
Change Mechanism ◽  
Different Temperatures ◽  
Temperature And Pressure

Temperature and pressure have direct and remarkable implications for drying and dewatering effect of low rank coals such as lignite. To understand the microenergy change mechanism of lignite, the molecular dynamics simulation method was performed to study the self-diffusion of lignite/water under different temperatures and pressure. The results showed that high temperature and high pressure can promote the diffusion of lignite/water system, which facilitates the drying and dewatering of lignite. The volume and density of lignite/water system will increase and decrease with temperature increasing, respectively. Though the pressure within simulation range can make lignite density increase, the increasing pressure showed a weak impact on variation of density.

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