Limits...
Energy landscapes of planar colloidal clusters.

Morgan JW, Wales DJ - Nanoscale (2014)

Bottom Line: The short-ranged potential is found to favour close-packed structures, with the potential energy primarily controlled by the number of nearest neighbour contacts.In the case of quasi-degeneracy the free energy global minimum may differ from the potential energy global minimum.This difference is due to symmetry effects, which result in a higher entropy for structures with lower symmetry.

View Article: PubMed Central - PubMed

Affiliation: University Chemical Laboratories, Lensfield Road, Cambridge CB2 1EW, UK.

ABSTRACT
A short-ranged pairwise Morse potential is used to model colloidal clusters with planar morphologies. Potential and free energy global minima as well as rearrangement paths, obtained by basin-hopping global optimisation and discrete path sampling, are characterised. The potential and free energy landscapes are visualised using disconnectivity graphs. The short-ranged potential is found to favour close-packed structures, with the potential energy primarily controlled by the number of nearest neighbour contacts. In the case of quasi-degeneracy the free energy global minimum may differ from the potential energy global minimum. This difference is due to symmetry effects, which result in a higher entropy for structures with lower symmetry.

No MeSH data available.


Plots of the Morse potential with ρ = 3, ρ = 14 and ρ = 30. The distance is in units of Re and the energy is in units of ε.
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fig1: Plots of the Morse potential with ρ = 3, ρ = 14 and ρ = 30. The distance is in units of Re and the energy is in units of ε.

Mentions: The interaction between two colloid particles is modelled using the Morse potential,17 written as1V = εeρ(1–R/Re)(eρ(1–R/Re) – 2),where Re is the equilibrium distance between the particles and ε is the energy at R = Re, so that ρ is a parameter that controls the range of the potential.17 The longer-range Morse potential, with ρ ≈ 3, has been used to study sodium clusters, while a shorter range, with ρ ≈ 14 is more appropriate for clusters of C60.22 In the present work, ρ ≈ 30 is used, as for previous work on colloidal particles.10,27,36,37 The total energy for the clusters is simply the sum of all the pair energies. Plots of the potential for several values of ρ are shown in Fig. 1.


Energy landscapes of planar colloidal clusters.

Morgan JW, Wales DJ - Nanoscale (2014)

Plots of the Morse potential with ρ = 3, ρ = 14 and ρ = 30. The distance is in units of Re and the energy is in units of ε.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4263186&req=5

fig1: Plots of the Morse potential with ρ = 3, ρ = 14 and ρ = 30. The distance is in units of Re and the energy is in units of ε.
Mentions: The interaction between two colloid particles is modelled using the Morse potential,17 written as1V = εeρ(1–R/Re)(eρ(1–R/Re) – 2),where Re is the equilibrium distance between the particles and ε is the energy at R = Re, so that ρ is a parameter that controls the range of the potential.17 The longer-range Morse potential, with ρ ≈ 3, has been used to study sodium clusters, while a shorter range, with ρ ≈ 14 is more appropriate for clusters of C60.22 In the present work, ρ ≈ 30 is used, as for previous work on colloidal particles.10,27,36,37 The total energy for the clusters is simply the sum of all the pair energies. Plots of the potential for several values of ρ are shown in Fig. 1.

Bottom Line: The short-ranged potential is found to favour close-packed structures, with the potential energy primarily controlled by the number of nearest neighbour contacts.In the case of quasi-degeneracy the free energy global minimum may differ from the potential energy global minimum.This difference is due to symmetry effects, which result in a higher entropy for structures with lower symmetry.

View Article: PubMed Central - PubMed

Affiliation: University Chemical Laboratories, Lensfield Road, Cambridge CB2 1EW, UK.

ABSTRACT
A short-ranged pairwise Morse potential is used to model colloidal clusters with planar morphologies. Potential and free energy global minima as well as rearrangement paths, obtained by basin-hopping global optimisation and discrete path sampling, are characterised. The potential and free energy landscapes are visualised using disconnectivity graphs. The short-ranged potential is found to favour close-packed structures, with the potential energy primarily controlled by the number of nearest neighbour contacts. In the case of quasi-degeneracy the free energy global minimum may differ from the potential energy global minimum. This difference is due to symmetry effects, which result in a higher entropy for structures with lower symmetry.

No MeSH data available.