Publications (2)2.55 Total impact
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ABSTRACT: Using density-functional molecular dynamics simulations we analysed the different steps that permit us to create a glass starting from a crystal in the case of GeS2. Thus we studied, mainly from a structural point of view, α-GeS2 crystals, GeS2 liquid at 2000 K and the evolution of the system during the quench. We found that in the liquid a first sharp diffraction peak exists even though the atoms are in a diffusive state. During the quench we evaluated the lifetime of the different interatomic bonds and we showed that the 'wrong' bonds present in the liquid can be destroyed and re-created several times during the length of the quench. Thus the ultra-fast cooling rates used in simulations cannot solely be held responsible for the structural differences that may be found between experimental and simulated glasses.Journal of Physics Condensed Matter 10/2007; 19(45):455207. · 2.55 Impact Factor
Article: On the influence of the initial liquid configuration on the structure of a glass obtained using ab-initio molecular dynamics simulations[show abstract] [hide abstract]
ABSTRACT: We describe the effect of the cooling rate on some structural properties of GeS2 chalcogenide glasses obtained using ab-initio molecular dynamics simulations. Quenches have been carried out using a linear velocity rescaling according to T(t) = T0 − γt where γ is the cooling rate. In the present paper we discuss the influence of the initial liquid configuration on the structure of the GeS2 glass. Structural properties of both liquid and glassy samples are compared. Furthermore a special attention is given to the total neutron structure factor. The decrease of the cooling rate appears in particular to improve the description of the medium range order of the glassy structure. The evolution of both intensity and position of the first sharp diffraction peak with the cooling rate also reveals that the influence of the initial configuration is very limited. Therefore our results confirm that in ab-initio molecular dynamics simulations as in experiment, the quench is the crucial step for structural changes between the liquid and the glassy phase.Journal of Non-Crystalline Solids.