Computer simulation study of a nematogenic lattice-gas model based on the Nehring-Saupe interaction potential

摘要

Over 25 years ago, Nehring and Saupe proposed an anisotropic nematogenic lattice model, whose restriction to nearest neighbours has the form U-jk/is an element of = Phi (jk) = -3/2(3a(j)a(k) - tau (jk))(2) +1 r = x(j) - x(k), r = /r/, a(j) = (u(j) (.)r)/r, a(k) = (u(k)(.)r)/r, tau (jk) = u(j) (.) u(k), Here the three-component vectors x(j) is an element of Z(3) define centre-of-mass coordinates of the particles, and uk are three-component unit vectors defining their orientations; E is a positive quantity setting energy and temperature scales (i.e. T* = k(B)T/is an element of); this model is seen to be the anisotropic counterpart to the generic Lebwohl-Lasher lattice model. It has often been used for approximate calculations of elastic properties, and has recently been studied by simulation [Hashim and Romano, Int. J. Mod. Phys. B13, 3879 (1999)1. We study here its lattice-gas extension, whose Hamiltonian is defined by Lambda/is an element of= Psi = Sigma ({j