Structure, Energetics, and Dynamics of Screw Dislocations in even n-Alkane Crystals

Isabel A. Olson, Alexander G. Shtukenberg, Gagik Hakobyan, Andrew L. Rohl, Paolo Raiteri, Michael D. Ward, Bart Kahr

Research output: Contribution to journalArticle

Abstract

Spiral hillocks on n-alkane crystal surfaces were observed immediately after Frank recognized the importance of screw dislocations for crystal growth, yet their structures and energies in molecular crystals remain ill-defined. To illustrate the structural chemistry of screw dislocations that are responsible for plasticity in organic crystals and upon which the organic electronics and pharmaceutical industries depend, molecular dynamics was used to examine heterochiral dislocation pairs with Burgers vectors along [001] in n-hexane, n-octane, and n-decane crystals. The cores were anisotropic and elongated in the (110) slip plane, with significant local changes in molecular position, orientation, conformation, and energy. This detailed atomic level picture produced a distribution of strain consistent with linear elastic theory, giving confidence in the simulations. Dislocations with doubled Burgers vectors split into pairs with elementary displacements. These results suggest a pathway to understanding the mechanical properties and failure associated with elastic and plastic deformation in soft crystals.

Original languageEnglish (US)
Pages (from-to)3112-3117
Number of pages6
JournalJournal of Physical Chemistry Letters
Volume7
Issue number16
DOIs
StatePublished - Aug 18 2016

ASJC Scopus subject areas

  • Materials Science(all)
  • Physical and Theoretical Chemistry

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