Structural probe of a glass-forming liquid: Generalized compressibility

Abstract

We introduce a new quantity to probe the glass transition. This quantity is a linear generalized compressibility which depends solely on the positions of the particles. We have performed a molecular dynamics simulation on a glass forming liquid consisting of a two component mixture of soft spheres in three dimensions. As the temperature is lowered (or as the density is increased), the generalized compressibility drops sharply at the glass transition, with the drop becoming more and more abrupt as the measurement time increases. At our longest measurement times, the drop occurs approximately at the mode coupling temperature TC . The drop in the linear generalized compressibility occurs at the same temperature as the peak in the specific heat. By examining the inherent structure energy as a function of temperature, we find that our results are consistent with the kinetic view of the glass transition in which the system falls out of equilibrium. We find no size dependence and no evidence for a second order phase transition though this does not exclude the possibility of a phase transition below the observed glass transition temperature. We discuss the relation between the linear generalized compressibility and the ordinary isothermal compressibility as well as the static structure factor.

Nonaffine Deformation of Inherent Structure as a Static Signature of Cooperativity in Supercooled Liquids

“…Remarkably, there are clearly two well distinguished temperature regimes for the typical length of the mismatch vectors. In addition, the transition between them becomes steeper for small and takes place at the onset of the cooperative dynamic regime (T ' 0:4), i.e., very close to T eIS , where the IS energy starts to strongly depend on temperature, and well above structural arrest (T MCT ' 0:303) [15,17].…”

“…Main frame: The participation ratio Å as a function of the temperature for the 3D binary mixture of Ref [15],. in the case of the spatially modulated deformation (i) of amplitude ¼ 10 À4 , 10 À3 , 10 À2 .…”

“…Inset: Average degree of correlation CðrÞ of the direction of the mismatch vectors separated by a distance r for ¼ 0:01. color online). Normalized mean length of mismatch field l d ð; TÞ=l d ð; T ¼ 1Þ as a function of T in the 3D binary mixture of Ref [15],. obtained with the spatially modulated deformation (i) of amplitude and wave vector k 1 .…”

Orbital order-disorder transition inLa1−xNdxMnO3(Bhattacharya1, Devi2, Maiti3 2004Phys. Rev. B142160View full textAdd to dashboardCite

“…13 controversial. 16 There is another possibility. In systems with local lattice distortions or defects, one can observe a local first order transition yet a global rounding of the transition due to wide distribution of the transition point.…”

Crystal Phases of Glass-Forming Mixtures

“…Binary mixtures have been employed in modelling glass-forming alloys, using Lennard-Jones [6,7,8] or soft sphere potentials (in 3D [9,10,11] and 2D [12,13]). Despite the considerable effort in characterising glassy behaviour in binary mixtures of spherical particles interacting via Lennard-Jones or repulsive r -12 potentials, information about the stable crystalline phases and the equilibrium transition temperatures of these systems is, at best, incomplete.…”