The favored cluster structures of model glass formers

Doye, Jonathan P. K.; Wales, David J.; Zetterling, Fredrik H. M.; Dzugutov, Mikhail

doi:10.1063/1.1534831

Cited by 89 publications

(98 citation statements)

References 42 publications

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“…This pair potential is characterized by the presence of two repulsive regions and one attractive region. The potential is designed to favor local icosahedral ordering 51,52 and is considered a generic model of simple metallic liquids, which have icosahedral coordination of the first neighbor shell. Further information about the model is found in refs 43 and 51.…”

Section: Model and Simulationmentioning

confidence: 99%

Spatially Heterogeneous Dynamics and the Adam−Gibbs Relation in the Dzugutov Liquid

et al. 2005

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We perform molecular dynamics simulations of a one-component glass-forming liquid and use the inherent structure formalism to test the predictions of the Adam-Gibbs (AG) theory and to explore the possible connection between these predictions and spatially heterogeneous dynamics. We calculate the temperature dependence of the average potential energy of the equilibrium liquid and show that it obeys the RosenfeldTarazona T 3/5 law for low temperature T, while the average inherent structure energy is found to be inversely proportional to temperature at low T, consistent with a Gaussian distribution of potential energy minima. We investigate the shape of the basins around the local minima in configuration space via the average basin vibrational frequency and show that the basins become slightly broader upon cooling. We evaluate the configurational entropy S conf , a measure of the multiplicity of potential energy minima sampled by the system, and test the validity of the AG relation between S conf and the bulk dynamics. We quantify the dynamically heterogeneous motion by analyzing the motion of particles that are mobile on short and intermediate time scales relative to the characteristic bulk relaxation time. These mobile particles move in one-dimensional "strings", and these strings form clusters with a well-defined average cluster size. The AG approach predicts that the minimum size of cooperatively rearranging regions (CRR) of molecules is inversely proportional to S conf , and recently (Phys. Rev. Lett. 2003, 90, 085506) it has been shown that the mobile-particle clusters are consistent with the CRR envisaged by Adam and Gibbs. We test the possibility that the mobile-particle strings, rather than clusters, may describe the CRR of the Adam-Gibbs approach. We find that the strings also follow a nearly inverse relation with S conf . We further show that the logarithm of the time when the strings and clusters are maximum, which occurs in the late--relaxation regime of the intermediate scattering function, follows a linear relationship with 1/TS conf , in agreement with the AG prediction for the relationship between the configurational entropy and the characteristic time for the liquid to undergo a transition to a new configuration. Since strings are the basic elements of the clusters, we propose that strings are a more appropriate measure of the minimum size of a CRR that leads to configurational transitions. That the cluster size also has an inverse relationship with S conf may be a consequence of the fact that the clusters are composed of strings.

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Section: Model and Simulationmentioning

confidence: 99%

Spatially Heterogeneous Dynamics and the Adam−Gibbs Relation in the Dzugutov Liquid

et al. 2005

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“…Crystallization then requires a rearrangement of the local structure of the liquid, which leads to a strong first-order freezing transition and allows supercooling of the liquid. Since then, there has been a large body of experimental and simulation work confirming the prevalence of local icosahedral, or more generally polytetrahedral, order in atomic liquids and metallic glasses [2,5,6,7,8,9,10,11,12,13,14,15].…”

Section: Introductionmentioning

confidence: 99%

“…The tendency to form icosahedral order has been shown to increase as the temperature is lowered [2,9,10,11,12,13,14,15]. …”

Section: Introductionmentioning

confidence: 99%

Locally preferred structure in simple atomic liquids

Mossa

Tarjus

2003

The Journal of Chemical Physics

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We propose a method to determine the locally preferred structure of model liquids. This latter is obtained numerically as the global minimum of the effective energy surface of clusters formed by small numbers of particles embedded in a liquid-like environment. The effective energy is the sum of the intra-cluster interaction potential and of an external field that describes the influence of the embedding bulk liquid at a mean-field level. Doing so we minimize the surface effects present in isolated clusters without introducing the full blown geometrical frustration present in bulk condensed phases. We find that the locally preferred structure of the Lennard-Jones liquid is an icosahedron, and that the liquid-like environment only slightly reduces the relative stability of the icosahedral cluster. The influence of the boundary conditions on the nature of the ground-state configuration of Lennard-Jones clusters is also discussed.

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“…The LFS for this system was identfied as the icosahedron following an analysis of local environments of the constituent particles [14]. Subsequently one of us investigated the lifetimes of 33 different structures, chosen to minimise the local potential energy [58,59]. Of these, the icosahedron was found to last around a decade longer than other structures with a distinct bond topology [18].…”

Section: Introductionmentioning

confidence: 99%

Structure in sheared supercooled liquids: Dynamical rearrangements of an effective system of icosahedra

Pinney

Liverpool

Royall

2016

The Journal of Chemical Physics

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We consider a binary Lennard-Jones glassformer whose super-Arrhenius dynamics are correlated with the formation of particles organized into icosahedra under simple steady state shear. We recast this glassformer as an effective system of icosahedra [Pinney et al. J. Chem. Phys. 143 244507 (2015)]. From the observed population of icosahedra in each steady state, we obtain an effective temperature which is linearly dependent on the shear rate in the range considered. Upon shear banding, the system separates into a region of high shear rate and a region of low shear rate. The effective temperatures obtained in each case show that the low shear regions correspond to a significantly lower temperature than the high shear regions. Taking a weighted average of the effective temperature of these regions (weight determined by region size) yields an estimate of the effective temperature which compares well with an effective temperature based on the global mesocluster population of the whole system.

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The favored cluster structures of model glass formers

Cited by 89 publications

References 42 publications

Spatially Heterogeneous Dynamics and the Adam−Gibbs Relation in the Dzugutov Liquid

Spatially Heterogeneous Dynamics and the Adam−Gibbs Relation in the Dzugutov Liquid

Locally preferred structure in simple atomic liquids

Structure in sheared supercooled liquids: Dynamical rearrangements of an effective system of icosahedra

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