Statistical temperature molecular dynamics simulations applied to phase transitions in liquid crystalline systems

Abstract

The recently developed statistical temperature molecular dynamics (STMD) method [Kim et al., Phys. Rev. Lett. 97, 050601 (2006)] is applied to the simulation of liquid crystalline soft matter systems. Results are presented demonstrating how, in combination with anisotropic soft core potentials, STMD simulation is able to sample efficiently across a large temperature window; and thus bridge across isotropic-liquid crystal phase transitions. Data is presented for two separate systems, namely, a single-site interaction model and an AB rod-coil block copolymer. The results are in excellent agreement with phase diagrams calculated by a series of traditional canonical molecular dynamics simulations bridging similar temperature/energy windows. In addition to the usual energetic and structural information, the STMD technique provides the temperature dependence of the entropy, free energy and heat capacity of the system as by-products of the single simulation. The combined soft-core/STMD strategy is presented as an effective means of scanning the phase diagram of a simple molecular interaction model to understand the relationship between molecular structure and phase behavior.