02096nas a2200169 4500008004100000022001400041245010200055210006900157260012500226300001100351490000800362520135300370100002401723700002201747700003401769856012301803 2013 eng d a0021-960600aNon-monotonic size dependence of diffusion and levitation effect: a mode-coupling theory analysis0 aNonmonotonic size dependence of diffusion and levitation effect  aCIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USAbAMER INST PHYSICScMAR a1245050 v1383 a

We present a study of diffusion of small tagged particles in a solvent, using mode coupling theory (MCT) analysis and computer simulations. The study is carried out for various interaction potentials. For the first time, using MCT, it is shown that only for strongly attractive interaction potential with allowing interpenetration between the solute-solvent pair the diffusion exhibits a non-monotonic solute size dependence which has earlier been reported in simulation studies [P. K. Ghorai and S. Yashonath, J. Phys. Chem. B 109, 5824-5835 (2005)]. For weak attractive and repulsive potential the solute size dependence of diffusion shows monotonic behaviour. It is also found that for systems where the interaction potential does not allow solute-solvent interpenetration, the solute cannot explore the neck of the solvent cage. Thus these systems even with strong attractive interaction will never show any non-monotonic size dependence of diffusion. This non-monotonic size dependence of diffusion has earlier been connected to levitation effect [S. Yashonath and P. Santikary, J. Phys. Chem. 98, 6368 (1994)]. We also show that although levitation is a dynamic phenomena, the effect of levitation can be obtained in the static radial distribution function. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4796232]

1 aNandi, Manoj, Kumar1 aBanerjee, Atreyee1 aBhattacharyya, Sarika, Maitra uhttp://library.ncl.res.in/content/non-monotonic-size-dependence-diffusion-and-levitation-effect-mode-coupling-theory-001825nas a2200193 4500008004100000022001400041245009300055210006900148260008700217300001100304490000800315520106800323100002401391700002201415700002501437700002101462700003401483856011401517 2015 eng d a0021-960600aUnraveling the success and failure of mode coupling theory from consideration of entropy0 aUnraveling the success and failure of mode coupling theory from  a1305 WALT WHITMAN RD, STE 300, MELVILLE, NY 11747-4501 USAbAMER INST PHYSICScNOV a1745040 v1433 a

We analyze the dynamics of model supercooled liquids in a temperature regime where predictions of mode coupling theory (MCT) are known to be valid qualitatively. In this regime, the Adam-Gibbs (AG) relation, based on an activation picture of dynamics, also describes the dynamics satisfactorily, and we explore the mutual consistency and interrelation of these descriptions. Although entropy and dynamics are related via phenomenological theories, the connection between MCT and entropy has not been argued for. In this work, we explore this connection and provide a microscopic derivation of the phenomenological Rosenfeld theory. At low temperatures, the overlap between the MCT power law regime and AG relation implies that the AG relation predicts an avoided divergence at T-c, the origin of which can be related to the vanishing of pair configurational entropy, which we find occurring at the same temperature. We also show that the residual multiparticle entropy plays an important role in describing the relaxation time. (C) 2015 AIP Publishing LLC.

1 aNandi, Manoj, Kumar1 aBanerjee, Atreyee1 aSengupta, Shiladitya1 aSastry, Srikanth1 aBhattacharyya, Sarika, Maitra uhttp://library.ncl.res.in/content/unraveling-success-and-failure-mode-coupling-theory-consideration-entropy-102078nas a2200181 4500008004100000022001400041245012600055210006900181260008700250300002700337490000800364520129300372100002201665700002401687700002101711700003401732856013001766 2016 eng d a0021-960600aEffect of total and pair configurational entropy in determining dynamics of supercooled liquids over a range of densities0 aEffect of total and pair configurational entropy in determining  a1305 WALT WHITMAN RD, STE 300, MELVILLE, NY 11747-4501 USAbAMER INST PHYSICScJUL aArticle Number: 0345020 v1453 a

In this paper, we present a study of supercooled liquids interacting with the Lennard Jones potential and the corresponding purely repulsive (Weeks-Chandler-Andersen) potential, over a range of densities and temperatures, in order to understand the origin of their different dynamics in spite of their structures being similar. Using the configurational entropy as the thermodynamic marker via the Adam Gibbs relation, we show that the difference in the dynamics of these two systems at low temperatures can be explained from thermodynamics. At higher densities both the thermodynamical and dynamical difference between these model systems decrease, which is quantitatively demonstrated in this paper by calculating different parameters. The study also reveals the origin of the difference in pair entropy despite the similarity in the structure. Although the maximum difference in structure is obtained in the partial radial distribution function of the B type of particles, the rdf of AA pairs and AB pairs gives rise to the differences in the entropy and dynamics. This work supports the observation made in an earlier study [A. Banerjee et al., Phys. Rev. Lett. 113, 225701 (2014)] and shows that they are generic in nature, independent of density. Published by AIP Publishing.

1 aBanerjee, Atreyee1 aNandi, Manoj, Kumar1 aSastry, Srikanth1 aBhattacharyya, Sarika, Maitra uhttp://library.ncl.res.in/content/effect-total-and-pair-configurational-entropy-determining-dynamics-supercooled-liquids-over01287nas a2200169 4500008004100000245008600041210006900127260000800196300002700204490000800231520067600239100002200915700002400937700002100961700003400982856010101016 2017 eng d00aDetermination of onset temperature from the entropy for fragile to strong liquids0 aDetermination of onset temperature from the entropy for fragile  cJUL aArticle Number: 0245040 v1473 a

In this paper, we establish a connection between the onset temperature of glassy dynamics with the change in the entropy for a wide range of model systems. We identify the crossing temperature of pair and excess entropies as the onset temperature. Below the onset temperature, the residual multiparticle entropy, the difference between excess and pair entropies, becomes positive. The positive entropy can be viewed as equivalent to the larger phase space exploration of the system. The new method of onset temperature prediction from entropy is less ambiguous, as it does not depend on any fitting parameter like the existing methods. Published by AIP Publishing.

1 aBanerjee, Atreyee1 aNandi, Manoj, Kumar1 aSastry, Srikanth1 aBhattacharyya, Sarika, Maitra uhttp://library.ncl.res.in/content/determination-onset-temperature-entropy-fragile-strong-liquids01588nas a2200157 4500008004100000245010500041210006900146260000800215490000800223520097600231100002401207700002201231700002201253700003401275856012101309 2017 eng d00a Role of the pair correlation function in the dynamical transition predicted by mode coupling theory0 aRole of the pair correlation function in the dynamical transitio cDEC0 v1193 aIn a recent study, we have found that for a large number of systems the configurational entropy at the pair level S-c2, which is primarily determined by the pair correlation function, vanishes at the dynamical transition temperature T-c. Thus, it appears that the information of the transition temperature is embedded in the structure of the liquid. In order to investigate this, we describe the dynamics of the system at the mean field level and, using the concepts of the dynamical density functional theory, show that the dynamical transition temperature depends only on the pair correlation function. Thus, this theory is similar in spirit to the microscopic mode coupling theory (MCT). However, unlike microscopic MCT, which predicts a very high transition temperature, the present theory predicts a transition temperature that is similar to T-c. This implies that the information of the dynamical transition temperature is embedded in the pair correlation function.1 aNandi, Manoj, Kumar1 aBanerjee, Atreyee1 aDasgupta, Chandan1 aBhattacharyya, Sarika, Maitra uhttp://library.ncl.res.in/content/role-pair-correlation-function-dynamical-transition-predicted-mode-coupling-theory01758nas a2200157 4500008004100000245012200041210006900163260000800232300001200240490000800252520112900260100002201389700002401411700003401435856013101469 2017 eng d00aValidity of the Rosenfeld relationship: a comparative study of the network forming NTW model and other simple liquids0 aValidity of the Rosenfeld relationship a comparative study of th cJUL a793-8000 v1293 aIn this paper we explore the validity of the Rosenfeld and the Dzugutov relation for the Lennard-Jones (LJ) system, its repulsive counterpart, the WCA system and a network forming liquid, the NTW model. We find that for all the systems both the relations are valid at high temperature regime with an universal exponent close to 0.8. Similar to that observed for the simple liquids, the LJ and the WCA systems show a breakdown of the scaling laws at the low temperature regime. However for the NTW model, which is a simple liquid, these scaling laws are valid even at lower temperature regime similar to that found for ionic melts. Thus we find that the NTW model has mixed characteristics of simple liquids and ionic melts. Our study further reveals a quantitative relationship between the Rosenfeld and the Arrhenius relations. For strong liquids, the validity of the Rosenfeld relation in the low temperature regime is connected to it following the Arrhenius behaviour in that regime. Finally we explore the role of pair entropy and residual multiparticle entropy in the dynamics as a function of fragility of the systems.1 aBanerjee, Atreyee1 aNandi, Manoj, Kumar1 aBhattacharyya, Sarika, Maitra uhttp://library.ncl.res.in/content/validity-rosenfeld-relationship-comparative-study-network-forming-ntw-model-and-other-simple02136nas a2200157 4500008004100000022001400041245010000055210006900155260000800224300001100232490000800243520155600251100002401807700003401831856011301865 2018 eng d a0021-960600aAnalysis of the anomalous mean-field like properties of Gaussian core model in terms of entropy0 aAnalysis of the anomalous meanfield like properties of Gaussian  cJAN a0345040 v1483 a

Studies of the Gaussian core model (GCM) have shown that it behaves like a mean-field model and the properties are quite different from standard glass former. In this work, we investigate the entropies, namely, the excess entropy (Sex) and the configurational entropy (S-c) and their different components to address these anomalies. Our study corroborates most of the earlier observations and also sheds new light on the high and low temperature dynamics. We find that unlike in standard glass former where high temperature dynamics is dominated by two-body correlation and low temperature by many-body correlations, in the GCM both high and low temperature dynamics are dominated by many-body correlations. We also find that the many-body entropy which is usually positive at low temperatures and is associated with activated dynamics is negative in the GCM suggesting suppression of activation. Interestingly despite the suppression of activation, the Adam-Gibbs (AG) relation that describes activated dynamics holds in the GCM, thus suggesting a non-activated contribution in AG relation. We also find an overlap between the AG relation and mode coupling power law regime leading to a power law behavior of S-c. From our analysis of this power law behavior, we predict that in the GCM the high temperature dynamics will disappear at dynamical transition temperature and below that there will be a transition to the activated regime. Our study further reveals that the activated regime in the GCM is quite narrow. Published by AIP Publishing.

1 aNandi, Manoj, Kumar1 aBhattacharyya, Sarika, Maitra uhttp://library.ncl.res.in/content/analysis-anomalous-mean-field-properties-gaussian-core-model-terms-entropy02315nas a2200265 4500008004100000022001400041245008000055210006900135260000800204300001100212490000900223520150000232653001001732653000901742653002301751653002001774653002501794653001201819653002001831100001901851700002401870700002201894700003401916856009901950 2019 eng d a1742-546800aComparative study of a class of mean field theories of the glass transition0 aComparative study of a class of mean field theories of the glass cAUG a0840080 v20193 a

In a recently developed microscopic mean field theory, we have shown that the dynamics of a system, when described only in terms of its pair structure, can predict the correct dynamical transition temperature. Further, the theory predicted the difference in dynamics of two systems (the Lennard-Jones and the Weeks-Chandler-Andersen) despite them having quite similar structures. This is in contrast to the Schweizer-Saltzman (SS) formalism which predicted the dynamics of these two systems to be similar. The two theories although similar in spirit have certain differences. Here we present a comparative study of these two formalism to find the origin of the difference in their predictive power. We show that not only the dynamics in the potential energy surface, as described by our earlier study, but also that in the free energy surface, like in the SS theory, can predict the correct dynamical transition temperature. Even an approximate one component version of our theory, similar to the system used in the SS theory, can predict the transition temperature reasonably well. Interestingly, we show here that despite the above mentioned shortcomings the SS theory can actually predict the correct transition temperatures. Thus microscopic mean field theories of this class which express dynamics in terms of the pair structure of the liquid while being unable to predict the actual dynamics of the system are successful in predicting the correct dynamical transition temperature.

10aaging10aetc)10aglasses (colloidal10aglassy dynamics10amode coupling theory10aPolymer10aslow relaxation1 aSaha, Indranil1 aNandi, Manoj, Kumar1 aDasgupta, Chandan1 aBhattacharyya, Sarika, Maitra uhttp://library.ncl.res.in/content/comparative-study-class-mean-field-theories-glass-transition02885nas a2200193 4500008004100000022001400041245012500055210006900180260000800249300001100257490000700268520214500275653003202420653002502452653003002477100002402507700003402531856012602565 2020 eng d a0953-898400aContinuous time random walk concepts applied to extended mode coupling theory: a study of the Stokes? Einstein breakdown0 aContinuous time random walk concepts applied to extended mode co cFEB a0640010 v323 a

In an attempt to extend the mode coupling theory (MCT) to lower temperatures, some years back an Unified theory was proposed which within the MCT framework incorporated the activated dynamics via the random first order transition theory (RFOT). The theory successfully showed that there is hopping induced diffusive dynamics and the modified MCT coupled to the activated motion continues till low temperatures. Here we show that the theory although successful in describing other properties of supercooled liquids is unable to capture the Stokes?Einstein breakdown. We then show using continuous time random work (CTRW) formalism that the Unified theory is equivalent to a CTRW dynamics in presence of two waiting time distributions. It is known from earlier work on CTRW that in such cases the total dynamics is dominated by the fast motion. This explains the failure of the Unified theory in predicting the SE breakdown as both the structural relaxation and the diffusion process are described by the comparatively fast MCT like dynamics. The study also predicts that other forms of extended MCT with Markovian hopping kernel will face a similar issue. We next modify the Unified theory by applying the concept of renewal theory, usually used in CTRW models where the distribution has a long tail. According to this theory the first jump given by the persistent time is slower than the subsequent jumps given by the exchange time. We first show that for systems with two waiting time distributions even when both the distributions are exponential the persistent time is larger than the exchange time. We also identify the persistent time with the slower activated process. The extended Unified theory can now explain the SE breakdown. In this extended theory at low temperatures the structural relaxation is described by the activated dynamics whereas the diffusion is primarily determined by the MCT like dynamics leading to a decoupling between them. We also calculate a dynamic lengthscale from the wavenumber dependence of the relaxation time. We find that this dynamic length scale grows faster than the static length scale.

10acontinuous time random walk10amode coupling theory10aStokes?Einstein breakdown1 aNandi, Manoj, Kumar1 aBhattacharyya, Sarika, Maitra uhttp://library.ncl.res.in/content/continuous-time-random-walk-concepts-applied-extended-mode-coupling-theory-study-stokes02090nas a2200181 4500008004100000022001400041245006700055210006700122260000900189300001100198490000800209520150000217100001701717700002401734700002501758700003401783856009101817 2021 eng d a0021-960600aEffective structure of a system with continuous polydispersity0 aEffective structure of a system with continuous polydispersity cJAN  a0345030 v1543 a

In a system of N particles, with continuous size polydispersity, there exists an N(N - 1) number of partial structure factors, making it analytically less tractable. A common practice is to treat the system as an effective one component system, which is known to exhibit an artificial softening of the structure. The aim of this study is to describe the system in terms of M pseudospecies such that we can avoid this artificial softening but, at the same time, have a value of M << N. We use potential energy and pair excess entropy to estimate an optimum number of species, M-0. We then define the maximum width of polydispersity, Delta sigma (0), that can be treated as a monodisperse system. We show that M-0 depends on the degree and type of polydispersity and also on the nature of the interaction potential, whereas Delta sigma (0) weakly depends on the type of polydispersity but shows a stronger dependence on the type of interaction potential. Systems with a softer interaction potential have a higher tolerance with respect to polydispersity. Interestingly, M-0 is independent of system size, making this study more relevant for bigger systems. Our study reveals that even 1% polydispersity cannot be treated as an effective monodisperse system. Thus, while studying the role of polydispersity by using the structure of an effective one component system, care must be taken in decoupling the role of polydispersity from that of the artificial softening of the structure.

1 aPatel, Palak1 aNandi, Manoj, Kumar1 aNandi, Ujjwal, Kumar1 aBhattacharyya, Sarika, Maitra uhttp://library.ncl.res.in/content/effective-structure-system-continuous-polydispersity01655nas a2200157 4500008004100000022001400041245005800055210005800113260000900171300001100180490000800191520115400199100002401353700003401377856008601411 2021 eng d a0031-900700aMicroscopic theory of softness in supercooled liquids0 aMicroscopic theory of softness in supercooled liquids cMAY  a2080010 v1263 a

We introduce a new measure of the structure of a liquid which is the softness of the mean-field potential developed by us earlier. We find that this softness is sensitive to small changes in the structure. Then, we study its correlation with the supercooled liquid dynamics. The study involves a wide range of liquids (fragile, strong, attractive, repulsive, and active) and predicts some universal behaviors such as the softness being linearly proportional to the temperature and inversely proportional to the activation barrier of the dynamics with system dependent proportionality constants. We establish a master equation between the dynamics and the softness parameter and show that, indeed, the dynamics, when scaled by the temperature and system dependent parameters, show a data collapse when plotted against softness. The dynamics of fragile liquids show a strong softness dependence, whereas that of strong liquids show a much weaker softness dependence. We also connect the present study with the earlier studies of softness involving machine learning (ML), thus, providing a theoretical framework for understanding the ML results.

1 aNandi, Manoj, Kumar1 aBhattacharyya, Sarika, Maitra uhttp://library.ncl.res.in/content/microscopic-theory-softness-supercooled-liquids01744nas a2200169 4500008004100000022001400041245009700055210006900152260000800221300001100229490000800240520113000248100001801378700002401396700003401420856012001454 2022 eng d a2470-004500aIdentifying structural signature of dynamical heterogeneity via the local softness parameter0 aIdentifying structural signature of dynamical heterogeneity via  cAPR a0446040 v1053 a

In this work we study the relationship between the softness of a mean-field caging potential and dynamics at the local level. We first describe the local softness, which shows a distribution, thus identifying structural heterogeneity. We show that the lifetime of the softness parameter is connected to the lifetime of the well-known cage structure in supercooled liquids. Finally, our theory predicts that the local softness and the local dynamics is causal below the onset temperature where there is a decoupling between the short and long time dynamics, thus allowing a static description of the cage. With the decrease in temperature, the correlation between structure and dynamics increases. The study shows that at lower temperatures, the structural heterogeneity increases, and since the structure becomes a better predictor of the dynamics, it leads to an increase in the dynamical heterogeneity. We also find that the softness of a hard, immobile region evolves with time and becomes soft and eventually mobile due to the rearrangements in the neighborhood, confirming the well-known facilitation effect.

1 aSharma, Mohit1 aNandi, Manoj, Kumar1 aBhattacharyya, Sarika, Maitra uhttp://library.ncl.res.in/content/identifying-structural-signature-dynamical-heterogeneity-local-softness-parameter02480nas a2200241 4500008004100000022001400041245016600055210006900221260000900290300001100299490000800310520158300318100002501901700001701926700001501943700002401958700002501982700002302007700002202030700002202052700003402074856013002108 2022 eng d a0021-960600aThermodynamics and its correlation with dynamics in a mean-field model and pinned systems: a comparative study using two different methods of entropy calculation0 aThermodynamics and its correlation with dynamics in a meanfield  cJAN  a0145030 v1563 aA recent study introduced a novel mean-field model system where each particle over and above the interaction with its regular neighbors interacts with k extra pseudo-neighbors. Here, we present an extensive study of thermodynamics and its correlation with the dynamics of this system. We surprisingly find that the well-known thermodynamic integration (TI) method of calculating the entropy provides unphysical results. It predicts vanishing of the configurational entropy at temperatures close to the onset temperature of the system and negative values of the configurational entropy at lower temperatures. Interestingly, well below the temperature at which the configurational entropy vanishes, both the collective and the single-particle dynamics of the system show complete relaxation. Negative values of the configurational entropy are unphysical, and complete relaxation when the configurational entropy is zero violates the prediction of the random first-order transition theory (RFOT). However, the entropy calculated using the two-phase thermodynamics (2PT) method remains positive at all temperatures for which we can equilibrate the system, and its values are consistent with RFOT predictions. We find that with an increase in k, the difference in the entropy computed using the two methods increases. A similar effect is also observed for a system where a randomly selected fraction of the particles are pinned in their positions in the equilibrated liquid. We show that the difference in entropy calculated via the 2PT and TI methods increases with pinning density.1 aNandi, Ujjwal, Kumar1 aPatel, Palak1 aMoid, Mohd1 aNandi, Manoj, Kumar1 aSengupta, Shiladitya1 aKarmakar, Smarajit1 aMaiti, Prabal, K.1 aDasgupta, Chandan1 aBhattacharyya, Sarika, Maitra uhttp://library.ncl.res.in/content/thermodynamics-and-its-correlation-dynamics-mean-field-model-and-pinned-systems-comparative