Melting of Lennard-Jones rare-gas clusters doped with a single impurity atom

Abstract

Single impurity effect on the melting process of magic number Lennard-Jones, rare gas, clusters of up to 309 atoms is studied on the basis of Parallel Tempering Monte Carlo simulations in the canonical ensemble. A decrease on the melting temperature range is prevalent, although such effect is dependent on the size of the impurity atom relative to the cluster size. Additionally, the difference between the atomic sizes of the impurity and the main component of the cluster should be considered. We demonstrate that solid-solid transitions due to migrations of the impurity become apparent and are clearly differentiated from the melting up to cluster sizes of 147 atoms.

Impurity effects on solid–solid transitions in atomic clusters

“…6a exhibits additional low-temperature peaks that also change with σ r . Analogous C V features have been reported previously 19 and attributed to dopant delocalisation prior to melting. Here we also interpret these features as indicators of non-degenerate permutational isomerisation (see below), and the fact that they change systematically with σ r indicates potentially tunable behaviour.…”

“…This result is consistent with previous experiments 10,11 and calculations. [12][13][14][15][16]18,19 More importantly, we have shown that a given solid-solid transition supports only a limited range of atom-size mismatch, and exceeding the system-specific limits will destroy the transition. Hence, a transition temperature can be tuned only by impurities with mismatch magnitude below a certain tolerance, which is generally larger for surface (as opposed to interior) impurities.…”

“…In the present study we focus on solid-solid transitions, where one solidlike phase is supplanted by a distinctly different one prior to complete melting, and we explore how such transitions are affected when the atomic identity of a single substituent is varied. We consider various models and set three main objectives: (i) to qualitatively compare with previous experimental 10,11 and computational [12][13][14][15][16][17][18][19] studies examining impurity/dopant effects on cluster melting; (ii) to discern generic behaviour that could be exploited for tuning various thermal instabilities in nanoalloys; and (iii) to demonstrate how the harmonic superposition approach (HSA) 20,21 can be used to identify and explain impurity effects in atomic clusters at temperatures below melting.…”

Thermodynamic Properties of Ga27Si3 Cluster Using Density Functional Molecular Dynamics

“…The distortion of the system lattice leads to the change in energetics as well as entropy of the cluster. The reduction of the melting temperature of magic Lennard-Jones clusters due to a single impurity has also been observed …”

Molecular dynamics simulations of the impurity effect on packing structures, local stresses, and thermodynamics of Ih silver clusters

“…14 In addition, single atom impurities in pure component clusters can also cause doping effects, such as the change of melting temperature or the solid-solid transition at low temperatures. 15,16 Experimental results show that the addition of a carbon atom to small-size Ni clusters can change the thermodynamic properties of these Ni clusters. And the existence of carbon impurities can significantly change the migration and diffusion of atoms in the Ni clusters at temperatures close to the melting point.…”