Quantum effects on dislocation motion from ring-polymer molecular dynamics

作     者：Rodrigo Freitas Mark Asta Vasily V.Bulatov 

作者机构：Department of Materials Science and EngineeringUniversity of CaliforniaBerkeleyCA 94720USA Lawrence Livermore National LaboratoryLivermoreCA 94550USA Materials Sciences DivisionLawrence Berkeley National LaboratoryBerkeleyCA 94720USA Department of Materials Science and EngineeringStanford UniversityStanfordCA 94305USA 

出 版 物：《npj Computational Materials》 (计算材料学（英文）)

年 卷 期：2018年第4卷第1期

页      面：198-203页

核心收录：

学科分类：07[理学] 0805[工学-材料科学与工程（可授工学、理学学位）] 070201[理学-理论物理] 0701[理学-数学] 0801[工学-力学（可授工学、理学学位）] 0702[理学-物理学] 0812[工学-计算机科学与技术（可授工学、理学学位）] 

基　　金：M.A.was supported by the U.S.Department of Energy,Office of Science,Office of Basic Energy Sciences,Materials Sciences and Engineering Division under Contract No.DE-AC02-05-CH11231(Mechanical Behavior of Materials Program(KC13) This work was performed under the auspices of the US Department of Energy by Lawrence Livermore National Laboratory under contract W-7405-Eng-48 

主　　题：theory quantum motion 

摘      要：Quantum motion of atoms known as zero-point vibration was recently proposed to explain a long-standing discrepancy between theoretically computed and experimentally measured low-temperature plastic strength of iron and possibly other metals with high atomic *** finding challenges the traditional notion that quantum motion of atoms is relatively unimportant in solids comprised of heavy *** we report quantum dynamic simulations of quantum effects on dislocation motion within the exact formalism of Ring-Polymer Molecular Dynamics(RPMD).To extend the reach of quantum atomistic simulations to length and time scales relevant for extended defects in materials,we implemented RPMD in the open-source code LAMMPS thus making the RPMD method widely available to the *** use our RPMD/LAMMPS approach for direct calculations of dislocation mobility and its effects on the yield strength ofα-*** simulation results establish that quantum effects are noticeable at temperatures below 50 K but account for only a modest(≈13% at T=0 K)overall reduction in the Peierls barrier,at variance with the factor of two reduction predicted earlier based on the more approximate framework of harmonic transition state *** results confirm that zero-point vibrations provide ample additional agitation for atomic motion that increases with decreasing temperature,however its enhancing effect on dislocation mobility is largely offset by an increase in the effective atom size,an effect known as quantum dispersion that has not been accounted for in the previous calculations.