How does a crystal melt?

ORAL

Abstract

Melting is one of the most important yet poorly understood phenomena. Nucleation and growth of melt play a key role in melting processes, and occur at sub-ns and sub-ns scales which essentially preclude direct observation of the initial stages of melting. Inherent defects also complicates the whole process. An indispensable first step is to understand the melting of an initially defect and surface free solid, namely, homogeneous nucleation. A natural tool to decipher the physics of melting is molecular dynamics simulations on a simple system. We have conducted such simulations on Cu described by an accurate embedded atom method potential on system sizes ranging from $10^3$ to $10^6$ atoms. The structural evolution of the system is characterized with local and global order parameters, and the evolution of liquid, with cluster analysis. The size distribution of liquid nuclei is thus quantified for a single run. As fluctuations are ubiquitous and critical for phase transitions, we adopt the mean first passage time method to obtain statistically from 100 MD runs the critical nucleus size, Zeldovich factor and steady state nucleation rate. The nucleation and growth of melt, with the aid of fluctuations, are demonstrated by the simulations; classical nucleation theory can describe the nucleation process with reasonable accuracy, if the solid$-$liquid interface is properly considered. We also present shock wave induced melting of Cu single crystals.

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Authors

  • Sheng-Nian Luo

    Los Alamos National Lab

  • Seth Putterman

    Department of Chemistry and Biochemistry, Arizona State University, Tempe, AZ 85287, USA, Department of Physics, Arizona State University, Tempe, AZ 85287, USA, College of Optical Sciences, University of Arizona, Colorado State University, University of Virginia, Auburn University, Northern Kentucky University, Utah Valley State College, Brigham Young University, Arizona State University, University of Amsterdam, New Mexico State university, University of Minesota, Pulse Field Facility, NHMFL, LANL, NM, Institute of Physics ASCR , Czech Republic, University of Minesota-Twin City, New Mexico State University, Director, Advanced Photon Source, Argonne National Lab, Australian Synchotron Source, Advanced Photon Source, Argonne National Lab, University of Arizona, U.S. Naval Research Laboratory, Wellesley College, Observatoire de Paris, France, Freie Universitat Berlin, Florida State Univ., Univ. Sci. Tech. China, Iowa State University, Lawrence Livermore National Laboratory, Mahabad Azad University, Carnegie Mellon University, Tempe Preparatory Academy, University of California, Los Angeles

  • Seth Putterman

    Department of Chemistry and Biochemistry, Arizona State University, Tempe, AZ 85287, USA, Department of Physics, Arizona State University, Tempe, AZ 85287, USA, College of Optical Sciences, University of Arizona, Colorado State University, University of Virginia, Auburn University, Northern Kentucky University, Utah Valley State College, Brigham Young University, Arizona State University, University of Amsterdam, New Mexico State university, University of Minesota, Pulse Field Facility, NHMFL, LANL, NM, Institute of Physics ASCR , Czech Republic, University of Minesota-Twin City, New Mexico State University, Director, Advanced Photon Source, Argonne National Lab, Australian Synchotron Source, Advanced Photon Source, Argonne National Lab, University of Arizona, U.S. Naval Research Laboratory, Wellesley College, Observatoire de Paris, France, Freie Universitat Berlin, Florida State Univ., Univ. Sci. Tech. China, Iowa State University, Lawrence Livermore National Laboratory, Mahabad Azad University, Carnegie Mellon University, Tempe Preparatory Academy, University of California, Los Angeles