Temperature and mass dependence of anharmonic defect dynamics

Salamatov, E. I.

doi:10.1002/pssb.2221970207

Cited by 13 publications

(3 citation statements)

References 3 publications

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“…6͒ which takes into account the anharmonicity effects within the framework of a pseudoharmonic self-consistent phonon approximation. 7 In the present work we calculate from first principles the P-T phase diagram of Zr in the Debye model and demonstrate that this simplified approach is quite sufficient for the problem under consideration. Earlier, we carried out an analogous investigation of the Ti interfaces which gave a good agreement with experiments.…”

Section: Introductionmentioning

confidence: 66%

Calculation of theP−Tphase diagram of Zr in different approximations for the exchange-correlation energy

Ostanin

Trubitsin

1998

Phys. Rev. B

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The full-potential linear muffin-tin orbital method is used within the local density approximation and generalized gradient approximation ͑GGA͒ to calculate the total energy and equilibrium lattice properties for the observed phases of Zr. The temperature dependences of the free energy, specific volume, bulk modulus, Debye temperature, and Grüneisen constant are found for these structures within the Debye model. For most quantities, a good quantitative agreement with experiment is obtained. The P-T phase diagram constructed from the calculated thermodynamical Gibbs potentials within the GGA fits well the available room-temperature data on the ␣→ and →␤ transitions. At ambient pressure, we get T ␤→␣ ϭ1193 K, which is close to the observed value. ͓S0163-1829͑98͒02514-4͔

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Section: Introductionmentioning

confidence: 66%

Calculation of theP−Tphase diagram of Zr in different approximations for the exchange-correlation energy

Ostanin

Trubitsin

1998

Phys. Rev. B

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“…The pseudoharmonic approximation can provide only a crude picture of the temperature behaviour of the anharmonic mode dynamics. A more rigorous approach [26] and numerical simulation [27] show that in a multi-well potential there is a probability of both basic (localized near the global and local minima) and excited vibrations at all temperatures. The density of the vibrational states of such an oscillator is represented by some peaks corresponding to these vibrations.…”

Section: Calculation Of the Temperature-dependent W Phonon Frequencymentioning

confidence: 99%

Calculation of the phonon frequencies of in an anharmonic model

Ostanin

Salamatov

1997

J. Phys.: Condens. Matter

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The equilibrium lattice constant and the bulk modulus of fcc Fe are calculated by the FP-LMTO method. The use of the generalized gradient approximation in calculating the electron structure and lattice properties of is discussed. A local minimum is observed on the curve of total energy versus the amplitude of the atomic displacements corresponding to transverse vibrations at the W point of the Brillouin zone. The temperature dependence of the anharmonic mode effective frequency calculated within the framework of the pseudoharmonic approximation is found to qualitatively agree with the experimental one. The possibility of interpreting the structural phase transition as a transition of the `active' phonon mode from the excited to the basic state is discussed.

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“…Using perturbation theory for the anharmonic effects, Chen et al [14] conclude that -Zr becomes stable at high temperatures as the result of interaction between different vibrations. The so-called modified PHA [18] takes into account intrinsic anharmonicity for some particular modes while its interactions with other vibrations come via a thermostat, i.e., the vibrational modes remain quasi-independent. In the case of Zr, the N-point phonon frequency, calculated within the modified PHA [16], is almost twice as large as the measured value.…”

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confidence: 99%

Lattice Dynamics of an Anharmonic Crystal: Evidence for Interactions between Atomic Vibrations at High Temperatures

Trubitsin

Ostanin²

2004

Phys. Rev. Lett.

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In studying the lattice dynamics of a strongly anharmonic crystal, we solve a set of nonlinear Langevin equations for interacting oscillators while a multiwell potential is calculated in the displacive limit from the first principles. The model applied to the peculiar vibrations of beta-Zr along [111] allows us to analyze all contributions to the spectral density and their influence on each other. We predict the effect of induced anharmonicity for quick vibrations due to their interaction with intrinsically anharmonic slow vibrations. This effect results in the broadband distribution in energy of inelastic neutron scattering known as the symmetry-forbidden phonon-branch splitting.

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Temperature and mass dependence of anharmonic defect dynamics

Cited by 13 publications

References 3 publications

Calculation of theP−Tphase diagram of Zr in different approximations for the exchange-correlation energy

Calculation of theP−Tphase diagram of Zr in different approximations for the exchange-correlation energy

Calculation of the phonon frequencies of in an anharmonic model

Lattice Dynamics of an Anharmonic Crystal: Evidence for Interactions between Atomic Vibrations at High Temperatures

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