Berlin 2008 – wissenschaftliches Programm

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SYMP: Symposium Computational Soft matter physics

SYMP 2: Computational soft matter physics

SYMP 2.6: Vortrag

Donnerstag, 28. Februar 2008, 16:30–16:45, H 0105

Non-cubic bicontinuous space partitions: transformation pathways between cubic lyotropic phases and possible equilibrium structures — •Gerd E Schröder-Turk — Inst. für Theoretische Physik I, Universität Erlangen-Nürnberg, Staudtstraße 7, 91058 Erlangen

Triply-periodic minimal surface families that contain the cubic Gyroid (G), Diamond (D) and Primitive (P) surfaces are studied in terms of their global packing and local curvature properties. These properties are central to understanding the formation of mesophases in amphiphile molecular systems. The surfaces investigated are the tetragonal, rhombohedral and hexagonal tD, tP, tG, rG, rPD and H surfaces. These non-cubic surfaces furnish topology-preserving transformation pathways between these cubic surfaces. We introduce ’packing homogeneity’, defined as the standard deviation Δ d of the distribution of the channel diameter throughout the labyrinth; the channel diameter d is determined from the medial surface skeleton centered within the domains. Curvature homogeneity is defined similarly as the standard deviation Δ K of the distribution of Gaussian curvature. We demonstrate that the cubic G and D surfaces are the most homogeneous members of these families. We show that the tetragonal pathway between the cubic phases to be more homogeneous than the rhombohedral one, relevant to pressure-induced phase transitions between these phases. We discuss the possibility of bicontinuous hexagonal equilibrium phases.