Microscopic mechanisms of equilibrium melting of a solid.
The melting of a solid, like other first-order phase transitions, exhibits an intrinsic time-scale disparity: The time spent by the system in metastable states is orders of magnitude longer than the transition times between the states. Using rare-event sampling techniques, we find that melting of representative solids-here, copper and aluminum-occurs via multiple, competing pathways involving the formation and migration of point defects or dislocations. Each path is characterized by multiple barrier-crossing events arising from multiple metastable states within the solid basin. At temperatures approaching superheating, melting becomes a single barrier-crossing process, and at the limit of superheating, the melting mechanism is driven by a vibrational instability. Our findings reveal the importance of nonlocal behavior, suggesting a revision of the perspective of classical nucleation theory.
Condensed Matter and Materials Division, Lawrence Livermore National Laboratory, Livermore, CA 94550 USA. Program in Applied and Computational Mathematics, Princeton University, Princeton, NJ 08544, USA. asamanta@math.princeton.edu weinan@math.princeton.edu mark.tuckerman@nyu.edu.
Amit
A
Samanta
Department of Chemistry, New York University (NYU), New York, NY 10003, USA. Courant Institute of Mathematical Sciences, NYU, New York, NY 10012, USA. NYU-East China Normal University Center for Computational Chemistry at NYU Shanghai, Shanghai 200062, China. asamanta@math.princeton.edu weinan@math.princeton.edu mark.tuckerman@nyu.edu.
Mark E
ME
Tuckerman
Courant Institute of Mathematical Sciences, NYU, New York, NY 10012, USA.
Tang-Qing
TQ
Yu
Beijing International Center for Mathematical Research and School of Mathematical Sciences, Peking University, Beijing, China. Department of Mathematics and Program in Applied and Computational Mathematics, Princeton University, Princeton, NJ 08544, USA. asamanta@math.princeton.edu weinan@math.princeton.edu mark.tuckerman@nyu.edu.
Weinan
W
E