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A structural path for the icosahedra <-> fcc structural transition in clusters

Ching-Ming Wei·Ching Cheng·Chun-Ming Chang
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Abstract

We propose a structural path for the icosahedra <-> fcc transition in clusters and demonstrate the transition in Pb_13 by ab initio molecular-dynamics simulation. The proposed path can be described by using only two variables. The energy surface on this two-dimensional space for Pb_13 was calculated and a barrierless fcc-to-ico energy path was found. The atomic displacements of the proposed structural transition for ico and fcc Pb_13 were identified as one of the vibrational eigenmodes of the clusters with a soft mode for fcc Pb_13. These agree with the energy curvatures around the two structures, i.e. the ico Pb_13 is at the bottom of a valley on the energy surface while the fcc Pb_13 is at a saddle point. The barriers of this transition for larger clusters of Pb_n (n=55, 147 and 309) were also calculated, by ab initio elastic-band method, and found being smaller than the room-temperature thermal energy.

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Ching-Ming Wei, Ching Cheng, Chun-Ming Chang. 2005-01-08. A structural path for the icosahedra <-> fcc structural transition in clusters. https://arxiv.org/abs/cond-mat/0501166

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