Ground-state clusters for short-range attractive and long-range repulsive potentials.
We report calculations of the ground-state energies and geometries for clusters of different sizes (up to 80 particles), where individual particles interact simultaneously via a short-ranged attractive potential, modeled with a generalization of the Lennard-Jones potential, and a long-ranged repulsive Yukawa potential. We show that for specific choices of the parameters of the repulsive potential, the ground-state energy per particle has a minimum at a finite cluster size. For these values of the parameters in the thermodynamic limit, at low temperatures and small packing fractions, where clustering is favored and cluster-cluster interactions can be neglected, thermodynamically stable cluster phases can be formed. The analysis of the ground-state geometries shows that the spherical shape is marginally stable. In the majority of the studied cases, we find that above a certain size, ground-state clusters preferentially grow almost in one dimension.
Mossa
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Dipartimento di Fisica and INFM Udr and SOFT, Complex Dynamics in Structured Systems, Università di Roma La Sapienza, P.le A. Moro 2, I-00185, Roma, Italy. mossa@esrf.fr
Sciortino
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Tartaglia
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Zaccarelli
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D008956:Models, Chemical; D008958:Models, Molecular; D015394:Molecular Structure; D049329:Nanostructures / Q000737:chemistry*; D010316:Particle Size; D013816:Thermodynamics