Non-monotonic size dependence of diffusion and levitation effect: A mode-coupling theory analysis

Nandi, Manoj Kumar; Banerjee, Atreyee; Bhattacharyya, S. K.

doi:10.1063/1.4796232

Cited by 5 publications

(15 citation statements)

References 36 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As shown in Fig.1a, the diffusion as a function of 1/σ sO does show a nonmonotonic behaviour with peak at σ sO 1. Note that, the position of the peak is similar to that obtained earlier 31,37,38 . The presence of such nonmonotonicity can be attributed to LE, i.e, for solutesolvent size σ sO 1 the solute, while passing through the neck of the transient solvent cage does not feel strong attraction due to force balance and this leads to the increase in the diffusion value.…”

Section: A Neutral Solutessupporting

confidence: 86%

“…The presence of such nonmonotonicity can be attributed to LE, i.e, for solutesolvent size σ sO 1 the solute, while passing through the neck of the transient solvent cage does not feel strong attraction due to force balance and this leads to the increase in the diffusion value. As discussed earlier 2, 35,[37][38][39][40] this force balance is specific to the size of the solute as compared to the size of the neck of the cage. The observation made from the present study is that at the point of levitation, where there is expected to be a force balance, the diffusion value is almost independent of interaction.…”

Section: A Neutral Solutesmentioning

confidence: 99%

See 1 more Smart Citation

Comparative Study of Anomalous Size Dependence of Charged and Neutral Solute Diffusion in Water

2019

Self Cite

View full text Add to dashboard Cite

In this work, we perform a comparative study of the size dependence of diffusion of charged and neutral solutes in water. The neutral solute in water shows a nonmonotonicity in the size dependence of diffusion. This is usually connected to the well known Levitation effect where it is found that when solute diffuses through the transient solvent cages then for attractive solute-solvent interaction and for a particular size of the solute there is a force balance which leads to the maximum in diffusion. Similar maximum in diffusion of charged solutes has also been observed and connected to Levitation effect. However, earlier studies of ionic diffusion connects this nonmonotonicity to the interplay between hard sphere repulsion and Coulombic attraction. In this work, we show that although the size dependence of both charged and neutral solutes have a nonmonotonicity, there is a stark difference in their behaviour. For charged solute with increase in attraction the maximum shifts to higher solute sizes and has a lower value whereas for neutral solute it remains at the same place and has a higher value. We show by studying the ionic and non-ionic part of the potential that for larger solutes it is the nonionic part which dominates and for smaller solutes the ionic part and the is a transition between them. As the charge on the solute increases, this transition takes place at larger solute sizes which leads to the shift in the diffusivity maxima and reduction of the peak value. We show that although the charged solutes also explore the solvent cage even before we reach the size which Levitates due to Coulombic attraction the diffusion value drops. Thus the origin of diffusivity maxima in charged and neutral solute diffusion is different.

show abstract

Section: A Neutral Solutessupporting

confidence: 86%

Section: A Neutral Solutesmentioning

confidence: 99%

Comparative Study of Anomalous Size Dependence of Charged and Neutral Solute Diffusion in Water

2019

Self Cite

View full text Add to dashboard Cite

show abstract

“…In an earlier work involving some of us we have shown that MCT calculations can explain the Levitation dynamics of small solute, even describing the non-monotonic solute size dependence of diffusion for an attractive solute-solvent interaction. 37 Given the success of MCT in earlier studies it is impetus to do a MCT calculations for our present systems. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 According to MCT the diffusion coefficient of a tagged solute particle can be written as, 39…”

Section: Mode Coupling Theory Predictionmentioning

confidence: 98%

“…31,37 The neck of the cage can be considered as an nanopore. The diffusion of a particle through a neck is similar to that along the pore axis.…”

Section: Our Modelmentioning

confidence: 99%

Diffusion of Small Solute Particles in Viscous Liquids: Cage Diffusion, a Result of Decoupling of Solute–Solvent Dynamics, Leads to Amplification of Solute Diffusion

et al. 2015

Self Cite

View full text Add to dashboard Cite

We study the diffusion of small solute particles through solvent by keeping the solute-solvent interaction repulsive and varying the solvent properties. The study involves computer simulations, development of a new model to describe diffusion of small solutes in a solvent, and also mode coupling theory (MCT) calculations. In a viscous solvent, a small solute diffuses via coupling to the solvent hydrodynamic modes and also through the transient cages formed by the solvent. The model developed can estimate the independent contributions from these two different channels of diffusion. Although the solute diffusion in all the systems shows an amplification, the degree of it increases with solvent viscosity. The model correctly predicts that when the solvent viscosity is high, the solute primarily diffuses by exploiting the solvent cages. In such a scenario the MCT diffusion performed for a static solvent provides a correct estimation of the cage diffusion.

show abstract

“…They could reproduce the velocity autocorrelation functions of various guest molecules in zeolite NaY [34]. Bhattacharyya and coworkers have carried out a mode coupling analysis of the levitation effect [35].…”

Section: Effect Of Temperature On the Levitation Effectmentioning

confidence: 99%

Anomalous Diffusivity in Porous Solids: Levitation Effect

Nag¹,

Yashonath²

2020

Zeolites - New Challenges

View full text Add to dashboard Cite

Fluids confined to zeolites and other porous solids exhibit many distinct properties. One such property is the diffusivity, which exhibits anomalous dependence on the size of the guest molecule confined to the pore. This is termed the levitation effect. A diffusivity maximum as a function of the diameter of the guest is seen. The diameter for which the guest has maximum diffusivity is seen to be associated with a minimum in the activation energy. The existence of similar behavior in other porous solids, framework flexibility, and effect of temperature are discussed. Experimental verification of the existence of the anomalous maximum is then discussed. Diffusion of n-hexane and its isomers in zeolite NaY are then discussed in detail. The reduction in the end-to-end length of n-hexane while passing through the 12-ring window and the reasons for the same are discussed. Section 3 discusses possible observations of size-dependent maximum in other condensed matter systems.

show abstract

Non-monotonic size dependence of diffusion and levitation effect: A mode-coupling theory analysis

Cited by 5 publications

References 36 publications

Comparative Study of Anomalous Size Dependence of Charged and Neutral Solute Diffusion in Water

Comparative Study of Anomalous Size Dependence of Charged and Neutral Solute Diffusion in Water

Diffusion of Small Solute Particles in Viscous Liquids: Cage Diffusion, a Result of Decoupling of Solute–Solvent Dynamics, Leads to Amplification of Solute Diffusion

Anomalous Diffusivity in Porous Solids: Levitation Effect

Contact Info

Product

Resources

About