RT Journal Article
T1 Biaxial nematic and smectic phases of parallel particles with different cross sections
A1 Martínez-Ratón, Yuri
A1 Varga, Szabolcs
A1 Velasco, Enrique
AB We have calculated the phase diagrams of one-component fluids made of five types of biaxial particles differing in their cross sections. The orientation of the principal particle axis is fixed in space, while the second axis is allowed to freely rotate. We have constructed a free-energy density functional based on fundamental-measure theory to study the relative stability of nematic and smectic phases with uniaxial, biaxial, and tetratic symmetries. Minimization of the density functional allows us to study the phase behavior of the biaxial particles as a function of the cross-section geometry. For low values of the aspect ratio of the particle cross section, we obtain smectic phases with tetratic symmetry, although metastable with respect to the crystal, as our Monte Carlo simulation study indicates. For large particle aspect ratios and in analogy with previous work [A. G. Vanakaras, M. A. Bates, and D. J. Photinos, Phys. Chem. Chem. Phys. 5, 3700 (2003)], we have found a four-phase point where four spinodals, corresponding to phase transitions between phases with different symmetries, meet together. The location of this point is quite sensitive to particle cross section, which suggests that optimizing the particle geometry could be a useful criterion in the design of colloidal particles that can exhibit an increased stability of the biaxial nematic phase with respect to other competing phases with spatial order.
PB The American Physical Society
SN 1539-3755
YR 2008
FD 2008-09
LK https://hdl.handle.net/10016/6982
UL https://hdl.handle.net/10016/6982
LA eng
NO 12 pages, 11 figures.-- PACS nrs.: 61.30.Cz, 61.30.Hn, 61.20.Gy.-- ArXiv pre-print available at: http://arxiv.org/abs/0806.2806
NO Y.M.-R. gratefully acknowledges financial support from Ministerio de Educación y Ciencia (Spain) under a Ramón y Cajal research contract and the MOSAICO grant. This work is part of the research Projects Nos. FIS2005-05243-C02-01 and FIS2007-65869-C03-01, also from Ministerio de Educacióny Ciencia, and Grant No. S-0505/ESP-0299 from Comunidad Autónoma de Madrid (Spain). Support from the Spanish-Hungarian "Integrated Actions" programme under Grant Nos. HH-2006-0005 is also acknowledged.
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