Nanocluster glass-formation: a potential energy landscape perspective

The intrinsic nature of glass states or glass transitions has been a mystery for a long time. Recent studies have suggested that glass-formation versus crystallization occurs for potential energy landscapes (PEL) having a specific structure and the present work is an elaboration of this perspective. To explore how the flatness of the PEL related to glass transition, we develop a method to adjust the PEL in a controllable manner. We demonstrate that a relatively flat PEL is not only necessary but also sufficient for the formation of a nanoscale glass. We show that: (1) as long as a nanocluster is located in a region of PEL with local minimum deep enough, it can undergo an abrupt thermodynamic transition reminiscent of the first order transition of bulk materials; and (2) if a nanocluster is located in a relatively flat PEL, it can undergo a very broad transition in their dynamics and thermodynamics that resembles glass-formation in bulk materials in many ways. All these transitions are independent of its structure symmetry, order or disorder. Our simulations also uncover the direct transition from one potential energy minimum to another below the glass transition temperature, which is the consequence of flat PELs.