A new approach to calculate the Peierls barrier of screw dislocations in bcc metals

0385290 - ÚFM 2013 RIV US eng C - Conference Paper (international conference)
Gröger, Roman
A new approach to calculate the Peierls barrier of screw dislocations in bcc metals.
Non-linear response of conventional & advanced materials, and multi-scale modeling. San Juan: NEAT Press, 2012, s. 100-103. ISBN 0-9659463-0-4.
[International Symposium on Plasticity and Its Current Applications /18./. San Juan (US), 03.01.2012-08.01.2012]
R&D Projects: GA ČR GAP204/10/0255; GA MŠMT(CZ) ED1.1.00/02.0068
Institutional research plan: CEZ:AV0Z20410507
Keywords : dislocation * Peierls barrier * Nudged Elastic Band
Subject RIV: BM - Solid Matter Physics ; Magnetism

We demonstrate that a straightforward application of the Nudged Elastic Band (NEB) method does not provide the correct Peierls barrier of 1/2111 screw dislocations in BCC metals. Although this method guarantees that the states of the system are distributed uniformly along the minimum energy path, it does not follow that the dislocation makes equal steps between neighboring images. The latter leads to clustering of images near potential minima and thus overestimation of the slope of the Peierls barrier. We propose a modification in which the NEB method is applied only to a few degrees of freedom that determine the position of the dislocation, while all other coordinates of atoms are relaxed. This “NEB method with relaxations” (NEB+r) provides the Peierls barrier for which the Peierls stress agrees well with that evaluated by the direct application of stress.
Permanent Link: http://hdl.handle.net/11104/0215251