Discovery of a paired Gaussian and long-tailed distribution of potential energies in nanoglasses

It is generally believed that the intrinsic properties of glasses are\nintimately related to potential-energy landscapes (PELs). However, little is\nknown about the PELs of glasses below the glass transition temperature (Tg).\nTaking advantage of lower potential-energy barriers in nanosystems, we have\nsystematically investigated the dynamics behavior of two nanoglasses, Al43 and\nAl46. Structure transformation is identified in our pure molecular-dynamics\nsimulation far below Tg, which manifests the existence of metabasins in PELs,\nat least for nanoglasses. Surprisingly, we find that the distribution of\npotential energies shows a paired Gaussian and long-tailed distribution at\ntemperatures below and approaching Tg; correspondingly, the distribution of the\n{\\alpha}-relaxation time exhibits an exponential-like decay. In contrast to the\nGaussian distribution of energy in typical liquids and solids, the unexpected\ndistribution may reflect the intrinsic feature of nanoglasses. Associated with\nthe exponential-like distribution of the {\\alpha}-relaxation time, the\nstretched-exponential structural relaxation is found, and the maximum stretched\nbehavior appears around Tg. Despite our studies focused on nanoglasses, the\ncurrent finding may shed light on future studies of bulk glasses.\n