Phase behavior of bent-core molecules

• Published in: Physical review. E, Statistical, nonlinear, and soft matter physics Vol. 67; no. 1 Pt 1; p. 011703
• Main Authors: Lansac, Yves, Maiti, Prabal K, Clark, Noel A, Glaser, Matthew A
• Format: Journal Article
• Language: English
• Published: United States 01.01.2003
• ISSN: 1539-3755
• DOI: 10.1103/PhysRevE.67.011703

Recently, a new class of smectic liquid crystal phases characterized by the spontaneous formation of macroscopic chiral domains from achiral bent-core molecules has been discovered. We have carried out Monte Carlo simulations of a minimal hard spherocylinder dimer model to investigate the role of excluded volume interactions in determining the phase behavior of bent-core materials and to probe the molecular origins of polar and chiral symmetry breaking. We present the phase diagram of hard spherocylinder dimers of length-diameter ratio of 5 as a function of pressure or density and dimer opening angle psi. With decreasing psi, a transition from a nonpolar to a polar smectic A phase is observed near psi=167 degrees, and the nematic phase becomes thermodynamically unstable for psi<135 degrees. Free energy calculations indicate that the antipolar smectic A (SmAP(A)) phase is more stable than the polar smectic A phase (SmAP(F)). No chiral smectic or biaxial nematic phases were found.