title: Impurity effects on solid-solid transitions in atomic clusters.
abstract: We use the harmonic superposition approach to examine how a single atom substitution affects low-temperature anomalies in the vibrational heat capacity (CV) of model nanoclusters. Each anomaly is linked to competing solidlike "phases", where crossover of the corresponding free energies defines a solid-solid transition temperature (Ts). For selected Lennard-Jones clusters we show that Tsand the corresponding CVpeak can be tuned over a wide range by varying the relative atomic size and binding strength of the impurity, but excessive atom-size mismatch can destroy a transition and may produce another. In some tunable cases we find up to two additional CVpeaks emerging below Ts, signalling one- or two-step delocalisation of the impurity within the ground-state geometry. Results for Ni74X and Au54X clusters (X = Au, Ag, Al, Cu, Ni, Pd, Pt, Pb), modelled by the many-body Gupta potential, further corroborate the possibility of tuning, engineering, and suppressing finite-system analogues of a solid-solid transition in nanoalloys.
authors: University Chemical Laboratories, Lensfield Road, Cambridge CB2 1EW, UK. Dmitri.Schebarchov@gmail.com dw34@cam.ac.uk and Department of Chemistry, Stanford University, Stanford, CA 94305, USA. bhusic@stanford.edu.
authors: B E
authors: BE
authors: Husic
authors: University Chemical Laboratories, Lensfield Road, Cambridge CB2 1EW, UK. Dmitri.Schebarchov@gmail.com dw34@cam.ac.uk.
authors: D
authors: D
authors: Schebarchov
authors: University Chemical Laboratories, Lensfield Road, Cambridge CB2 1EW, UK. Dmitri.Schebarchov@gmail.com dw34@cam.ac.uk.
authors: D J
authors: DJ
authors: Wales