About cookies on this site Our websites require some cookies to function properly (required). In addition, other cookies may be used with your consent to analyze site usage, improve the user experience and for advertising. For more information, please review your options. By visiting our website, you agree to our processing of information as described in IBM’sprivacy statement. To provide a smooth navigation, your cookie preferences will be shared across the IBM web domains listed here.
Publication
Physical Review B
Paper
Properties of the one-particle-displacement probability distribution in systems undergoing antiferrodistortive structural phase transitions
Abstract
Using the Hartree approximation, a high-temperature expansion, and the molecular-dynamics technique, we study some properties of the one-particle probability distribution F1(Ux1→) of the displacement Ux of particle one in a model system. The system is two dimensional and subjected to constraints in such a way that it exhibits antiferrodistortive structural phase transitions. It covers the displacive and order-disorder regime, including the Ising and displacive limit. We present evidence that F1(Ux1→) or its symmetrized analog F1(Ux1→)=12[F1(Ux1→)+F1(-Ux1→)], being a very useful property to elucidate the regime to which a particular antiferrodistortive transition belongs. In the displacive regime, the ratio as= ddUx1→F1(Ux1→)maxddUx1→F1(Ux1→)min, for Ux1→ either negative or positive, is shown to diverge at some temperature T*, because F1(Ux1→) exhibits for T<T* a double-peak structure disappearing at T=T*. In the order-disorder regime, the ratio T*Tc is infinite and decreases in the displacive regime by approaching the displacive limit to some value T*Tc<1. As Müller and Berlinger have shown, the key quantity as can be measured, close to Tc by means of the electron-paramagnetic-resonance technique. © 1974 The American Physical Society.