Publication

Incommensurately Modulated Structure of Gamma-Pamc - New Experimental Evidence For Amplitude and Phase Fluctuations

Gervais Chapuis
1994
Journal Articles

Abstract

The incommensurate structure of gamma-bis(n-propyl-ammonium) tetrachloromanganate(II) (gamma-PAMC) at 365 K has been determined in the superspace group Abma(alpha01)000. Main reflections and satellites up to second order have been included. Besides the harmonic model, anharmonic displacive and Debye-Waller factor modulations have been investigated. Anharmonicities of the displacive modulation functions are negligible. Global phason-correction terms significantly improve the agreement of the second-order satellites. Within the resolution of the experiment, the atomic amplitudon/phason correction converges to the expected theoretical values for the Mn and Cl atoms. The final agreement factors for a phason-corrected displacive harmonic modulation are R(all) = 0.052 (1056 reflections) [R(main) = 0.046 (369 reflections), R(1st order) = 0.057 (627 reflections), R(2nd order) = 0.137 (60 reflections)]. [References: 29]

Official source

https://infoscience.epfl.ch/entities/publication/e857e7bb-9b11-46ae-af37-171c4b818ac6

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Gervais Chapuis
1994
Journal Articles

Abstract

Official source

https://infoscience.epfl.ch/entities/publication/e857e7bb-9b11-46ae-af37-171c4b818ac6

About this result

Related concepts (24)

Harmonic oscillator

In classical mechanics, a harmonic oscillator is a system that, when displaced from its equilibrium position, experiences a restoring force F proportional to the displacement x: where k is a positive constant. If F is the only force acting on the system, the system is called a simple harmonic oscillator, and it undergoes simple harmonic motion: sinusoidal oscillations about the equilibrium point, with a constant amplitude and a constant frequency (which does not depend on the amplitude).

Simple harmonic motion

In mechanics and physics, simple harmonic motion (sometimes abbreviated ()) is a special type of periodic motion an object experiences due to a restoring force whose magnitude is directly proportional to the distance of the object from an equilibrium position and acts towards the equilibrium position. It results in an oscillation that is described by a sinusoid which continues indefinitely (if uninhibited by friction or any other dissipation of energy).

Quantum harmonic oscillator

The quantum harmonic oscillator is the quantum-mechanical analog of the classical harmonic oscillator. Because an arbitrary smooth potential can usually be approximated as a harmonic potential at the vicinity of a stable equilibrium point, it is one of the most important model systems in quantum mechanics. Furthermore, it is one of the few quantum-mechanical systems for which an exact, analytical solution is known.