Quantum relaxation, the shape of lattice absorption and inelastic neutron scattering lines

doi:10.1016/0022-3697(64)90122-2

Journal of Physics and Chemistry of Solids

Volume 25, Issue 5, May 1964, Pages 487-503

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Abstract

The fundamental optical lattice vibrations are treated as the system, the remaining lattice vibrations as the reservoir, and the anharmonic interactions as the coupling in a general density matrix theory of relaxation processes. An immediate result of this theory are expressions for frequency dependent level shifts and damping coefficients as well as corresponding frequency dependent coupling coefficients between the optical modes. If the coupling coefficients are neglected, and if in our expressions for the shift and damping coefficients anharmonic interactions in the reservoir are neglected our expressions simplify to those obtained by Wallis and Maradudin by summing an infinite ladder of diagrams.

By treating an arbitrary mode as the system and using the fluctuation-dissipation theorem, we derive the relation between the lifetime and shift of the mode and its contribution to the one-phonon inelastic neutron scattering line shape. The relaxation theory we use is based on a systematic improvement of the Hartree approximation in which the system and reservoir are treated in a symmetric fashion.

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Quantum relaxation, the shape of lattice absorption and inelastic neutron scattering lines

Abstract

Physica

Physica

Phys. Rev.

Sov. Phys.; Solid-State Phys.

Physica

Phys. Rev.

Dynamical Theory of Crystal Lattices

Phys. Rev.

Phys. Rev.

J. math. Phys.

Rep. on progr. Phys.

Rev. mod. Phys.

Rev. mod. Phys.

Rev. mod. Phys.

Phys. Rev.

Phys. Rev.

Phys. Rev.

Rev. mod. Phys.

J. Chem. Phys.

Phys. Rev.

Phys. Rev.

Phys. Rev.