02652nas a2200181   4500008004100000022001400041245010500055210006900160260008700229300002700316490000800343520189300351100002502244700002202269700002302291700003402314856012202348       2016                        eng d  a0021-960600aComposition dependence of the glass forming ability in binary mixtures: the role of demixing entropy0 aComposition dependence of the glass forming ability in binary mi  a1305 WALT WHITMAN RD, STE 300, MELVILLE, NY 11747-4501 USAbAMER INST PHYSICScJUL  aArticle Number: 0345030 v1453 a<p>We present a comparative study of the glass forming ability of binary systems with varying composition, where the systems have similar global crystalline structure (CsCl+fcc). Biased Monte Carlo simulations using umbrella sampling technique show that the free energy cost to create a CsCl nucleus increases as the composition of the smaller particles is decreased. We find that systems with comparatively lower free energy cost to form CsCl nucleus exhibit more pronounced pre-crystalline demixing near the liquid/crystal interface. The structural frustration between the CsCl and fcc crystal demands this demixing. We show that closer to the equimolar mixture, the entropic penalty for demixing is lower and a glass forming system may crystallize when seeded with a nucleus. This entropic penalty as a function of composition shows a non-monotonic behaviour with a maximum at a composition similar to the well known Kob-Anderson (KA) model. Although the KA model shows the maximum entropic penalty and thus maximum frustration against CsCl formation, it also shows a strong tendency towards crystallization into fcc lattice of the larger ``A'' particles which can be explained from the study of the energetics. Thus for systems closer to the equimolar mixture although it is the requirement of demixing which provides their stability against crystallization, for KA model it is not demixing but slow dynamics and the presence of the ``B'' particles make it a good glass former. The locally favoured structure around ``B'' particles is quite similar to the CsCl structure and the incompatibility of CsCl and fcc hinders the fcc structure growth in the KA model. Although the glass forming binary systems studied here are quite similar, differing only in composition, we find that their glass forming ability cannot be attributed to a single phenomenon. Published by AIP Publishing.</p>1 aNandi, Ujjwal, Kumar1 aBanerjee, Atreyee1 aChakrabarty, Suman1 aBhattacharyya, Sarika, Maitra  uhttps://library.ncl.res.in/content/composition-dependence-glass-forming-ability-binary-mixtures-role-demixing-entropy01954nas a2200169   4500008004100000022001400041245004900055210004800104260000800152300001100160490000800171520144900179100002501628700001601653700003401669856008101703       2021                        eng d  a0021-960600aConnecting real glasses to mean-field models0 aConnecting real glasses to meanfield models  cMAR  a0945060 v1543 a<p>We propose a novel model for a glass-forming liquid, which allows us to switch in a continuous manner from a standard three-dimensional liquid to a fully connected mean-field model. This is achieved by introducing k additional particle-particle interactions, which thus augments the effective number of neighbors of each particle. Our computer simulations of this system show that the structure of the liquid does not change with the introduction of these pseudo-neighbors and by means of analytical calculations, and we determine the structural properties related to these additional neighbors. We show that the relaxation dynamics of the system slows down very quickly with the increase in k and that the onset and the mode-coupling temperatures increase. The systems with high values of k follow the mode-coupling theory power law behavior for a larger temperature range compared to the ones with lower values of k. The dynamic susceptibility indicates that the dynamic heterogeneity decreases with the increase in k, whereas the non-Gaussian parameter is independent of it. Thus, we conclude that with the increase in the number of pseudo-neighbors, the system becomes more mean-field-like. By comparing our results with previous studies on mean-field-like systems, we come to the conclusion that the details of how the mean-field limit is approached are important since they can lead to different dynamical behavior in this limit.</p>
1 aNandi, Ujjwal, Kumar1 aKob, Walter1 aBhattacharyya, Sarika, Maitra  uhttps://library.ncl.res.in/content/connecting-real-glasses-mean-field-models