title: Phase diagram of octapod-shaped nanocrystals in a quasi-two-dimensional planar geometry.
abstract: Recently, we reported the formation of crystalline monolayers consisting of octapod-shaped nanocrystals (so-called octapods) that had arranged in a square-lattice geometry through drop deposition and fast evaporation on a substrate [W. Qi, J. de Graaf, F. Qiao, S. Marras, L. Manna, and M. Dijkstra, Nano Lett. 12, 5299 (2012)]. In this paper we give a more in-depth exposition on the Monte Carlo simulations in a quasi-two-dimensional (quasi-2D) geometry, by which we modelled the experimentally observed crystal structure formation. Using a simulation model for the octapods consisting of four hard interpenetrating spherocylinders, we considered the effect of the pod length-to-diameter ratio on the phase behavior and we constructed the full phase diagram. The methods we applied to establish the nature of the phase transitions between the various phases are discussed in detail. We also considered the possible existence of a Kosterlitz-Thouless-type phase transition between the isotropic liquid and hexagonal rotator phase for certain pod length-to-diameter ratios. Our methods may prove instrumental in guiding future simulation studies of similar anisotropic nanoparticles in confined geometries and monolayers.
authors.affiliation: Soft Condensed Matter, Debye Institute for Nanomaterials Science, Utrecht University, Princetonplein 5, 3584 CC Utrecht, The Netherlands. W.Qi@uu.nl
authors.forename: Weikai
authors.initials: W
authors.lastname: Qi
authors.forename: Joost
authors.initials: J
authors.lastname: de Graaf
authors.forename: Fen
authors.initials: F
authors.lastname: Qiao
authors.forename: Sergio
authors.initials: S
authors.lastname: Marras
authors.forename: Liberato
authors.initials: L
authors.lastname: Manna
authors.forename: Marjolein
authors.initials: M
authors.lastname: Dijkstra