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Aging to equilibrium dynamics of SiO2

Vollmayr-Lee, Katharina and Roman, Jeff A. and Horbach, Jürgen (2010) Aging to equilibrium dynamics of SiO2. Physical Review E, 81 (6), 061203. DOI: 10.1103/PhysRevE.81.061203. ISSN 1539-3755.

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Official URL: http://pre.aps.org/abstract/PRE/v81/i6/e061203

Abstract

Molecular dynamics computer simulations are used to study the aging dynamics of SiO2 (modeled by the BKS model). Starting from fully equilibrated configurations at high temperatures T-i is an element of {5000 K, 3760 K}, the system is quenched to lower temperatures T-f is an element of {2500 K, 2750 K, 3000 K, 3250 K} and observed after a waiting time t(w). Since the simulation runs are long enough to reach equilibrium at Tf, we are able to study the transition from out-of-equilibrium to equilibrium dynamics. We present results for the partial structure factors, for the generalized incoherent intermediate scattering function C-q(t(w), t(w) + t), and for the mean-square displacement Delta r(2)(t(w), t(w) + t). We conclude that there are three different t(w) regions: (I) At very short waiting times, C-q(t(w), t(w) + t) decays very fast without forming a plateau. Similarly Delta r(2)(t(w), t(w) + t) increases without forming a plateau. (II) With increasing tw a plateau develops in C-q(t(w), t(w) + t) and Delta r(2)(t(w), t(w) + t). For intermediate waiting times the plateau height is independent of t(w) and T-i. Time superposition applies, i.e., C-q=C-q(t/t(r)(Cq)) where t(r)(Cq)=t(r)(Cq)(t(w)) is a waiting time-dependent decay time. Furthermore C-q=C(q, t(w), t(w) + t) scales as C-q=C(q, z(t(w), t) where z is a function of t(w) and t only, i.e., independent of q. (III) At large t(w) the system reaches equilibrium, i.e., C-q(t(w), t(w) + t) and Delta r(2)(t(w), t(w) + t) are independent of t(w) and T-i. For C-q(t(w), t(w) + t) we find that the time superposition of intermediate waiting times (II) includes the equilibrium curve (III).

Document Type:Article
Title:Aging to equilibrium dynamics of SiO2
Authors:
AuthorsInstitution or Email of Authors
Vollmayr-Lee, KatharinaBucknell Univ., Lewisburg, USA
Roman, Jeff A.Bucknell Univ., Lewisburg, USA
Horbach, JürgenMP, DLR
Date:25 June 2010
Journal or Publication Title:Physical Review E
Refereed publication:Yes
In Open Access:No
In SCOPUS:Yes
In ISI Web of Science:Yes
Volume:81
DOI:10.1103/PhysRevE.81.061203
Page Range:061203
ISSN:1539-3755
Status:Published
Keywords:GLASS TRANSITION; COMPUTER SIMULATION; AGING
HGF - Research field:Aeronautics, Space and Transport (old)
HGF - Program:Space (old)
HGF - Program Themes:W FR - Forschung unter Weltraumbedingungen (old)
DLR - Research area:Space
DLR - Program:W FR - Forschung unter Weltraumbedingungen
DLR - Research theme (Project):W - Vorhaben Materialwissenschaftliche Forschung (old)
Location: Köln-Porz
Institutes and Institutions:Institute of Materials Physics in Space
Deposited By: Dr.rer.nat. Jürgen Horbach
Deposited On:05 Nov 2010 09:59
Last Modified:07 Feb 2013 20:39

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