Fizika Nizkikh Temperatur: Volume 44, Number 7 (July 2018), p. 877-886    ( to contents , go back )

Computer simulation and analytic description of the structural defects in two-dimensional limited in size crystals: free boundary, dislocations, crowdions

V.D. Natsik1,2, S.N. Smirnov1, and V.I. Belan1

1B. Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine 47 Nauky Ave., Kharkiv 61103, Ukraine

2V.N. Karazin Kharkiv National University, Kharkiv 61077, Ukraine
E-mail: smirnov@ilt.kharkov.ua

Received March 2, 2018

Abstract

2D limited in size crystals being generated of atoms with centrally symmetric interatomic interaction (the Lennard-Jones potential) were discussed. The atomic structure of approximately circular clusters of nanometer scale radius was established by molecular dynamics methods. The deviations of the atomic configurations from the perfect lattice of 2D crystal caused by both free boundary of cluster and interstitial defects in its centre (dislocation and crowdion) were investigated. The self energy of these defects was evaluated; their dependences on the cluster radius and the parameters of the interatomic interaction potential were analyzed. The features of homogeneous elastic deformation of 2D crystalline circle and band as compared to the deformation of 3D crystalline sphere and rod were described by continual mechanics methods. The two-dimensional analogues of fundamental elastic characteristics (modulus of compression, Young modulus, shear modulus, Poisson's ratio and their relation-ship with Lamé coefficients) were discussed. The dependences of the listed parameters of elasticity on the parameters of the interatomic interaction potential were established as well as the estimates of the effective core sizes of dislocation and crowdion were obtained.

PACS: 02.70.Ns Molecular dynamics and particle methods;
PACS: 07.05.Tp Computer modeling and simulation;
PACS: 61.72.Bb Theories and models of crystal de-fects;
PACS: 61.72.J– Point defects and defect clusters.

Key words: molecular dynamics computer simulation, two-dimensional crystals, moduli of elasticity, dislocations, crowdions, microscopic defect models, topological charge of defect, self energy of defects.

Published online: May 28, 2018

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