  We present Monte Carlo simulations of liquid-crystalline material confined to
a nanoscopic slit-pore. The simulations are carried out under isothermal
conditions in a specialized isostress ensemble in which N fluid molecules are
exposed to a compressional stress acting on the fluid in directions parallel
with the substrate planes. Fluid-fluid and fluid-substrate interactions are
modelled as in our previous work [M. Greschek et al., Soft Matter, 2010,
DOI:10.1039/B924417D). We study several anchoring mechanisms at the solid
substrate by introducing an anchoring function (0<g(u)<1) that depends on the
orientation of a fluid molecule relative to the substrate plane; g(u)
"switches" the fluid-substrate attraction on or off. Here we focus on various
heterogeneous (i.e., hybrid) anchoring scenarios imposing different anchoring
functions at the opposite substrates. As in our previous study we compute the
isostress heat capacity which allows us to identify states at which the
confined fluid undergoes a structural transformation. The isotropic-nematic
transformation turns out to be nearly independent of the specific anchoring
scenario. This is because the director in the nematic phase assumes a direction
that is a compromise between the directions enforced by the competing anchoring
scenarios at either substrate. On the contrary, at lower compressional stresses
molecules prealign in specific directions that depend on details of the
anchoring scenario.
