Thermodynamic behaviors of nano-sized au clusters on the (001) surface

초록

We have studied thermal expansion of the surface layers of the hexagonally reconstructed Au (001) surface using a classical Molecular Dynamics (MD) simulation technique with an Embedded Atomic Method (EAM) type many-body potential. We find that the top-most hexagonal layer contracts as temperature increases whereas the second layer expands or contracts depending on the size of system. The expansion coefficient of the top layer is much larger than the other layers, and the calculated thermal expansion coefficients are about -3.05 × 10-5and -4.93 × 10-5 Å/K. The Fast Fourier Transform (FFT) image of the atomic density shows that there exists a rotated domain of the topmost hexagonal cluster with rotation angle close to 1° at temperature T < 1000K. As the temperature increases this domain undergoes a surface orientational phase transition. These predictions are in a good agreement with previous phenomenological theories and experimental studies.

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