Atomic bond fluctuations and crossover to potential-energy-landscape-influenced regime in supercooled liquid.
The ideas related to potential-energy landscape and cooperativity of atomic rearrangements are widely discussed in the research field of glass transition. The crossover transition from high-temperature regime to potential-energy-landscape-influenced regime was extensively studied using the concept of inherent structure. However, the interpretation of this crossover behavior in terms of microscopic changes in real structures is still lacking. In this paper we present several observations on the crossover behavior on real structures. We compare fluctuations in the global properties (total number of bonds, total potential energy, pressure) versus fluctuations in the local properties (coordination number, atomic potential energy, local atomic pressure) by means of molecular dynamics simulations. We then show that the total and local fluctuations in the number of atomic bonds in the system depend on temperature differently above and below the temperature of crossover to the landscape-influenced regime. Similarly, the ratio between the global and local fluctuations in the potential energy and pressure changes in the vicinity of the crossover temperature, whereas the change is less distinct than in the case of the bond fluctuations. Our results indicate that local fluctuations become more correlated below the crossover temperature, most likely via the interaction through the dynamic shear elastic field.
Levashov
V A
VA
Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA.
Egami
T
T
Aga
R S
RS
Morris
J R
JR