Phase behaviour and correlations of parallel hard squares: from highly confined to bulk systems Articles uri icon

publication date

  • June 2016


  • 24


  • 28

international standard serial number (ISSN)

  • 0953-8984

electronic international standard serial number (EISSN)

  • 1361-648X


  • 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 (PY) theory, and compare the results with molecular dynamics and Monte Carlo simulations. In a second step, we study the confined system and check the results against those obtained from the transfer matrix method and from our own Monte Carlo simulations. Squares are confined to channels with parallel walls at angles of 0 degrees or 45 degrees 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 crystallization.


  • parallel hard squares; fundamental measure density functional; transfer matrix method; percus-yevick approximation; highly confined fluid; fundamental measure-theory; density-functional theory; white bear version; equation-of-state; free-energy model; dimensional crossover; sphere mixtures; cubes; fluid; particles