Numerical solution of the Onsager problem for an isotropic-nematic interface

The interfacial profile of the isotropic-nematic interface of a rigid-rod system is solved numerically based on a generalized Onsager model. For long rigid rods, the surface tension has the lowest value at a {π}/2 tilt angle between the nematic director and the normal to the interface. The density and order parameter are found to have different interfacial widths and interfacial positions. We find a dip in the density profile near the isotropic phase when the nematic director is almost parallel to the interfacial normal. The surface tension obtained here is 50% lower than the best variational calculation.