title: Structure, Energetics, and Dynamics of Screw Dislocations in Even n-Alkane Crystals.
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.
authors.affiliation: Department of Chemistry and Molecular Design Institute, New York University , New York City, New York 10003, United States.
authors.forename: Isabel A
authors.initials: IA
authors.lastname: Olson
authors.affiliation: Department of Chemistry and Molecular Design Institute, New York University , New York City, New York 10003, United States.
authors.forename: Alexander G
authors.initials: AG
authors.lastname: Shtukenberg
authors.affiliation: Department of Chemistry and Molecular Design Institute, New York University , New York City, New York 10003, United States.
authors.forename: Gagik
authors.initials: G
authors.lastname: Hakobyan
authors.affiliation: Curtin Institute for Computation and Department of Chemistry, Curtin University , P.O. Box U1987, Perth, Western Australia 6845, Australia.
authors.forename: Andrew L
authors.initials: AL
authors.lastname: Rohl
authors.affiliation: Curtin Institute for Computation and Department of Chemistry, Curtin University , P.O. Box U1987, Perth, Western Australia 6845, Australia.
authors.forename: Paolo
authors.initials: P
authors.lastname: Raiteri
authors.affiliation: Department of Chemistry and Molecular Design Institute, New York University , New York City, New York 10003, United States.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Ward
authors.affiliation: Department of Chemistry and Molecular Design Institute, New York University , New York City, New York 10003, United States.|Graduate School of Advanced Science and Engineering (TWIns), Waseda University , Tokyo, Japan.
authors.forename: Bart
authors.initials: B
authors.lastname: Kahr