Phase behaviour and correlations of parallel hard squares: From highly confined to bulk systems

Abstract

We study a fluid of two-dimensional parallel hard squares in bulk and under confinement in channels, with the aim of evaluating the performance of Fundamental-Measure Theory (FMT). To this purpose, we first analyse the phase behaviour of the bulk system using FMT and Percus-Yevick theory, and compare the results with MD and MC simulations. In a second step, we study the confined system and check the results against those obtained from Transfer Matrix Method and from our own Monte Carlo simulations. Squares are confined to channels with parallel walls at angles of 0${}^{\circ }$ or 45${}^{\circ }$ relative to the diagonals of the parallel hard squares, respectively, which allows for an assessment of the effect of the external-potential symmetry on the fluid structural properties. In general FMT overestimates bulk correlations, predicting the existence of a columnar phase (absent in simulations) prior to crystallisation. The equation of state predicted by FMT compares well with simulations, although the PY approach with the virial route is better in some range of packing fractions. The FMT is highly accurate for the structure and correlations of the confined fluid due to the dimensional crossover property fulfilled by the theory. Both density profiles and equations of state of the confined system are accurately predicted by the theory. The highly non-uniform pair correlations inside the channel are also very well described by FMT.

13 pages, 13 figures

References in corpus (9)

• Density functional theory for hard-sphere mixtures: the White-Bear version Mark II
• Tension and stiffness of the hard sphere crystal-fluid interface
• Hard-body models of bulk liquid crystals
• Understanding the ideal glass transition: Lessons from an equilibrium study of hard disks in a channel
• A fundamental-measure density functional for mixtures of parallel hard cylinders
• Phase behavior of parallel hard cylinders
• Surface tension of isotropic-nematic interfaces: Fundamental Measure Theory for hard spherocylinders
• Properties of non-FCC hard-sphere solids predicted by density functional theory
• Beyond the single-file fluid limit using transfer matrix method: Exact results for confined parallel hard squares

Cited by in corpus (5)

• Ordering of hard rectangles in strong confinement
• Ordering transitions of weakly anisotropic hard rods in narrow slit-like pores
• Capillary-driven biaxial planar and homeotropic nematization of hard cylinders
• Positional ordering of hard adsorbate particles in tubular nanopores
• Highly confined mixtures of parallel hard squares: A Density Functional Theory study