Reverse Monte Carlo methods

New Insights into Complex Materials Using Reverse Monte Carlo Modeling

“…In this manner, information about so-called rigid unit modes (RUMs)-the low-frequency, high-amplitude vibrational modes that do not distort the basic units of the structure-could be obtained. Results were indicative of the dynamic disorder in β-cristobalite being a superposition of many of the available RUMs and the decreased disorder in the α phase being the result of the reduction in the number of available RUMs (44,45).…”

“…RMC analysis applied to α-and β-quartz painted a very similar picture (2,45): Through the excitation of phonon modes, disorder increases in the α phase with temperature, prior to the eventual phase change, and is correlated with the degradation of piezoelectric properties at temperatures above 300 • C (46). For both quartz and cristobalite, the RMC models could be used to produce calculated diffuse scattering patterns that agreed extremely well with those measured from single crystals (2,44).…”

Three-dimensional structure of fast ion conducting 0.5Li2S+0.5[(1−x)GeS2+xGeO2] glasses from high-energy X-ray diffraction and reverse Monte Carlo simulations

“…Reverse Monte Carlo (RMC) simulations were employed to model the atomic-scale structure of 0.5Li 2 S + 0.5[(1 À x)GeS 2 + xGeO 2 ] glasses [19]. The method involves building of atomic configurations in a simulation box and refining them against experimental, structure-sensitive data such as S(Q) and g(r)'s.…”

Theory and Practice – Lattice Vibrations and Spectroscopy of Mantle Phases

“…Within crystals, the anharmonic nature of the interatomic potential generally causes the interatomic distances (r) to shift to larger values as T is increased: this results in the phenomenon of thermal expansion that is usually observed among minerals (however, some exceptions are well known, especially among framework mineral structures such as SiO 2 cristobalite and ZrW 2 O 6 (Mary et al, 1996;David et al, 1999;Heine et al, 1999;Mittal and Chaplot, 1999;Dove et al, 2002)). Vibrational frequencies generally shift to lower wave number with increasing T, and they increase with P, due to the asymmetric form of the interatomic potential energy function (Herzberg, 1950;McMillan, 1985).…”