02091nas a2200181 4500008004100000022001400041245006700055210006700122260000900189300001100198490000800209520150000217100001701717700002401734700002501758700003401783856009201817 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 uhttps://library.ncl.res.in/content/effective-structure-system-continuous-polydispersity02172nas a2200145 4500008004100000022001400041245015400055210006900209260000900278490000800287520155500295100001701850700003401867856012501901 2024 eng d a0021-960600aEffect of the presence of pinned particles on the structural parameters of a liquid and correlation between structure and dynamics at the local level0 aEffect of the presence of pinned particles on the structural par cAPR 0 v1603 a

Pinning particles at the equilibrium configuration of the liquid is expected not to affect the structure and any property that depends on the structure while slowing down the dynamics. This leads to a breakdown of the structure dynamics correlation. Here, we calculate two structural quantities: the pair excess entropy, S-2, and the mean field caging potential, the inverse of which is our structural order parameter (SOP). We show that when the pinned particles are treated the same way as the mobile particles, both S-2 and SOP of the mobile particles remain the same as those of the unpinned system, and the structure dynamics correlation decreases with an increase in pinning density, ``c.'' However, when we treat the pinned particles as a different species, even if we consider that the structure does not change, the expression of S-2 and SOP changes. The microscopic expressions show that the interaction between a pinned particle and a mobile particle affects S-2 and SOP more than the interaction between two mobile particles. We show that a similar effect is also present in the calculation of the excess entropy and is the primary reason for the well-known vanishing of the configurational entropy at high temperatures. We further show that, contrary to the common belief, the pinning process does change the structure. When these two effects are considered, both S-2 and SOP decrease with an increase in ``c,'' and the correlation between the structural parameters and the dynamics continues even for higher values of ``c.''

1 aPatel, Palak1 aBhattacharyya, Sarika, Maitra uhttps://library.ncl.res.in/content/effect-presence-pinned-particles-structural-parameters-liquid-and-correlation-between02306nas a2200181 4500008004100000022001400041245013100055210006900186260000800255300001100263490000800274520162500282100002001907700001701927700001801944700003401962856012801996 2024 eng d a0021-960600aExploring the soft pinning effect in the dynamics and the structure-dynamics correlation in multicomponent supercooled liquids0 aExploring the soft pinning effect in the dynamics and the struct cOCT a1545010 v1613 a

We study multicomponent liquids by increasing the mass of 15% of the particles in a binary Kob-Andersen model. We find that the heavy particles have dual effects on the lighter particles. At higher temperatures, there is a significant decoupling of the dynamics between heavier and lighter particles, with the former resembling a pinned particle to the latter. The dynamics of the lighter particles slow down due to the excluded volume around the nearly immobile heavier particles. Conversely, at lower temperatures, there is a coupling between the dynamics of the heavier and lighter particles. The heavier particles' mass slows down the dynamics of both types of particles. This makes the soft pinning effect of the heavy particles questionable in this regime. We demonstrate that as the mass of the heavy particles increases, the coupling of the dynamics between the lighter and heavier particles weakens. Consequently, the heavier the mass of the heavy particles, the more effectively they act as soft pinning centers in both high and low-temperature regimes. A key finding is that akin to the pinned system, the self-dynamics and collective dynamics of the lighter particles decouple from each other as the mass of the heavy particles has a more pronounced impact on the latter. We analyze the structure-dynamics correlation by considering the system under the binary and modified quaternary framework, the latter describing the pinned system. Our findings indicate that whenever the heavy mass particles function as soft pinning centers, the modified quaternary framework predicts a higher correlation.

1 aAnwar, Ehtesham1 aPatel, Palak1 aSharma, Mohit1 aBhattacharyya, Sarika, Maitra uhttps://library.ncl.res.in/content/exploring-soft-pinning-effect-dynamics-and-structure-dynamics-correlation-multicomponent