Melting of atomic solids: effect of range and softness of interaction potentials

Chakraborty, Somendra Nath; Ghosh, Nilanjan; Shah, Prasanna; Chakravarty, Charusita

doi:10.1080/00268970410001703345

Cited by 11 publications

(9 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It is interesting to note in this context that Morse systems with range parameter of 6 and the Lennard-Jones system have very similar melting behavior, in terms of molar entropies and molar volumes of fusion in reduced units. 39 In contrast, the melting behav-ior of softer Morse potentials, with α = 3, is expected to be similar to those of alkali metals. Figure 3(b) shows the potentials of mean force for the spherically averaged gold nanoparticle passivated with C 4 SH, C 6 SH, and C 12 SH in ethane solvent at a density of 2.5ρ c where ρ c is the critical density of the pure solvent.…”

Section: Pmf Profile For Au Sph -(Sc N ) 62mentioning

confidence: 99%

Fluctuation-driven anisotropy in effective pair interactions between nanoparticles: Thiolated gold nanoparticles in ethane

Jabes

Yadav

Kumar

et al. 2014

The Journal of Chemical Physics

View full text Add to dashboard Cite

Fluctuations within the ligand shell of a nanoparticle give rise to a significant degree of anisotropy in effective pair interactions for low grafting densities [B. Bozorgui, D. Meng, S. K. Kumar, C. Chakravarty, and A. Cacciuto, Nano Lett. 13, 2732 (2013)]. Here, we examine the corresponding fluctuation-driven anisotropy for gold nanocrystals densely passivated with short ligands. In particular, we consider gold nanocrystals capped by alkylthiols, both in vacuum and in ethane solvent at high density. As in the preceding study, we show that the anisotropy in the nanoparticle pair potential can be quantified by an angle-dependent correction term to the isotropic potential of mean force (PMF). We find that the anisotropy of the ligand shells is distance dependent, and strongly influenced by ligand interdigitation effects as well as expulsion of ligand chains from the interparticle region at short distances. Such fluctuation-driven anisotropy can be significant for alkylthiol-coated gold nanoparticles, specially for longer chain lengths, under good solvent conditions. The consequences of such anisotropy for self-assembly, specially as a function of grafting density, solvent quality and at interfaces, should provide some interesting insights in future work. Our results clearly show that an isotropic two-body PMF cannot adequately describe the thermodynamics and assembly behavior of nanoparticles in this dense grafting regime and inclusion of anisotropic effects, as well as possibly many-body interactions, is necessary. Extensions of this approach to other passivated nanoparticle systems and implications for self-assembly are considered.

show abstract

Section: Pmf Profile For Au Sph -(Sc N ) 62mentioning

confidence: 99%

Fluctuation-driven anisotropy in effective pair interactions between nanoparticles: Thiolated gold nanoparticles in ethane

Jabes

Yadav

Kumar

et al. 2014

The Journal of Chemical Physics

View full text Add to dashboard Cite

show abstract

“…Computational details regarding the Monte Carlo simulations are given elsewhere. 31 The three points along the melting line are shown in Table I which also lists the values of the perturbation theory parameters, as defined in Eqs. ͑16͒ and ͑17͒, at these state points.…”

Section: B Obtaining Solid-liquid Coexistence Conditionsmentioning

confidence: 99%

“…The q 6 order parameter has been found to be appropriate when considering melting of fcc solids. 31,37 Figure 9͑a͒ shows that there is a strong negative correlation between ␦ 2 and q 6 in the solid phase, i.e., atoms with large deviations from lattice positions will also tend to be in locally disordered environments with low q 6 values. The correlation is strong in the solid phase regardless of temperature or pressure, but the range of available ␦ 2 values clearly increases with temperature.…”

Section: -8mentioning

confidence: 99%

Lindemann measures for the solid-liquid phase transition

Chakravarty

Debenedetti²,

Stillinger

2007

The Journal of Chemical Physics

100

View full text Add to dashboard Cite

A set of Lindemann measures, based on positional deviations or return distances, defined with respect to mechanically stable inherent structure configurations, is applied to understand the solid-liquid phase transition in a Lennard-Jones-type system. The key quantity is shown to be the single-particle return distance-squared distribution. The first moment of this distribution is related to the Lindemann parameter which is widely used to predict the melting temperature of a variety of solids. The correlation of the single-particle return distance and local bond orientational order parameter in the liquid phase provides insights into mechanisms for melting. These generalized Lindemann measures, especially the lower order moments of the single-particle return distance distribution, show clear signatures of the transition of the liquid from the stable to the metastable, supercooled regime and serve as landscape-based indicators of the thermodynamic freezing transition for the Lennard-Jones-type system investigated.

show abstract

“…A path integral implementation of the Landau free energy method approach was also developed to study melting of quantum Lennard-Jones solids [16]. The Landau free energy approach has also been used to study the relationship between melting and the range and softness of interatomic potentials for Morse solids [17]. The range parameter of the Morse interaction was tuned to mimic the variation seen in atomic systems, from metallic systems with soft, long-range interactions to van der Waals solids with short-range, strongly repulsive potentials.…”

Section: Introductionmentioning

confidence: 99%

Relationship between crystalline order and melting mechanisms of solids

2009

View full text Add to dashboard Cite

The mechanism for homogeneous nucleation of the liquid phase in Lennard-Jones solids is studied by combining the Landau free energy approach with some of the methodology developed to characterise transition path ensembles. The second-order bond orientational order parameter, Q 6 which indexes the overall degree of crystalline order, is shown to provide a dynamically significant collective coordinate describing the melting process. Trajectories generated from configurations sampled in the vicinity of the maximum in the Landau free energy curve, F(Q 6 ), are shown to have equal likelihood of teminating in either the solid or liquid-like free energy minima. It is also demonstrated that Q 6 is necessary but not sufficient as a dynamical coordinate to describe melting and it is necessary to explore possiblities for additional coordinates which are critical for initiating melting. Our sudy suggests that the additional coordinates for describing the melting process would be some type of localised defect, much smaller in spatial extent than the size of the critical nucleus predicted by classical nucleation theory.

show abstract

Melting of atomic solids: effect of range and softness of interaction potentials

Cited by 11 publications

References 33 publications

Fluctuation-driven anisotropy in effective pair interactions between nanoparticles: Thiolated gold nanoparticles in ethane

Fluctuation-driven anisotropy in effective pair interactions between nanoparticles: Thiolated gold nanoparticles in ethane

Lindemann measures for the solid-liquid phase transition

Relationship between crystalline order and melting mechanisms of solids

Contact Info

Product

Resources

About