Simulation of the interaction between discrete breathers of various types in a Pt 3 Al crystal nanofiber
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Simulation of the Interaction between Discrete Breathers of Various Types in a Pt3Al Crystal Nanofiber P. V. Zakharova,b*, M. D. Starostenkovb, S. V. Dmitrievc,d, N. N. Medvedevb, and A. M. Eremina a
Shukshin Altai State Academy of Education, ul. Korolenko 53, Biisk, Altai krai, 659333 Russia b Polzunov Altai State Technical University, Biisk, Altai krai, 656038 Russia c Institute of Metals Superplasticity Problems, Russian Academy of Sciences, ul. Khalturina 39, Ufa, Bashkortostan, 450001 Russia d National Research Tomsk State University, Tomsk, 634050 Russia email: [email protected] Received February 9, 2015
Abstract—It is known that, in a molecular dynamics model of Pt3Al crystal, a discrete breather (DB) with soft type nonlinearity (DB1) can be excited, which is characterized by a high degree of localization on a light atom (Al), stationarity, as well as a frequency that lies in the gap of the phonon spectrum and decreases with increasing amplitude of the DB. In this paper, it is demonstrated that a DB with hard type nonlinearity (DB2) can be excited in a Pt3Al nanofiber; this DB is localized on several light atoms, can move along the crystal, and has a frequency that lies above the phonon spectrum and increases with the DB amplitude. It is notewor thy that the presence of free surfaces of a nanofiber does not prevent the existence of DB1 and DB2 in it. Col lisions of two DBs counterpropagating with equal velocities, as well as a collision of DB2 with a standing DB1, are considered. Two colliding DBs with hard type nonlinearity are repelled almost elastically, losing only insignificant part of their energy during the interaction. DB2 is also reflected from a standing DB1; in this case, the energy of the breathers is partially scattered into the Al sublattice. The results obtained indicate that DBs can transfer energy along a crystal over large distances. During the collision of two or more DBs, the energy localized in space can be as high as a few electronvolts; this allows one to raise the question of the participation of DBs in structural transformations of the crystal. DOI: 10.1134/S1063776115080154
1. INTRODUCTION Among various kinds of nanoobjects, special inter est has recently been devoted to nanofibers [1–8]. By nanofibers one usually means a bulk crystal that has almost no defects and whose transverse size is not greater than 100 nm [1]. Nanofibers are applied in a number of fields: medicine, bioengineering, electron ics, filtration of gases and liquids, and in the design of composite materials [6]. The wide scope of applica tions of nanofibers is attributed to their unique set of properties. The strength of nanofibers increases as their diameter decreases and approaches the theoreti cal limit [2–8]. The possibility of existence of soliton type objects (spatially localized nonlinear lattice exci tations) in nanofibers remains poorly studied in view of the complexity of fullscale experiments. Numeri cal experiments on the study of such excitations are carried out, as a ru
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