Supersonic voidions in 2D Morse lattice

• Published in: Chaos, solitons and fractals Vol. 140; p. 110217
• Main Authors: Shepelev, I.A., Dmitriev, S.V., Kudreyko, A.A., Velarde, M.G., Korznikova, E.A.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-11-2020
• Subjects: Atomistic simulations; Crowdions; Crystal lattice; Mass transfer; Nonliner dynamics; 05.45.Xt; Crystal lattice; Atomistic simulations; Nonliner dynamics; 89.75.Fb; Crowdions; Mass transfer
• ISSN: 0960-0779; 1873-2887
• DOI: 10.1016/j.chaos.2020.110217

•Molecular dynamics is used to study propagation of supersonic crowdion clusters.•Crowdions are initiated in three neighboring close-packed atomic rows.•Dynamics of crowdions cluster depends on the initial velocities of crowdions.•Supersonic motion of a vacancy is observed for particular choice of velocities.•Motion of a vacancy is explained through the formation of an extended vacancy.
Dynamics of M × 1-crowdion clusters (M=1, 2 or 3) and vacancy clusters is analyzed in 2D triangular lattice with Morse interactions. Topological defects are created in the lattice by kicking three neighboring atoms in the three neighboring close-packed atomic rows along the rows. Initial velocity of the atoms in the inner row, vinn, can be positive or negative, while the velocities of both atoms in the outer rows, vout, are equal and positive. The case of vinn=vout was analysed earlier and it was found that if the initial velocity is sufficiently large then a 3 × 1-crowdion cluster and a three-vacancy are formed. Two major effects are reported in the case of vinn ≠ vout analyzed here. (i) Due to the difference in the initial velocities, topological defects can be produced in the lattice with smaller initial energy than in the case of vinn=vout. (ii) In certain range of the initial velocities, a vacancy can appear at a distance of dozens interatomic distances from the initiation point, moving along the close-packed row with supersonic speed. Such moving vacancy is called voidion and mechanism of its formation and motion is revealed. Our results uncover new mechanisms of mass transfer by solitary waves in nonlinear lattices.