Bicritical points in a nematic rod-disk mixture

The influence of the rod-disk excluded volume on the existence of a bicritical point in a mixture of rodlike and disklike particles has been examined using the second virial theory. Within the approximation in which the interaction kernel is expanded to second order in a basis of symmetry-adapted functions, it is shown from a combination of bifurcation analysis and numerical solution of the Euler-Lagrange equations for the free energy that there exists a value of the rod-disk excluded volume parameter for which the bicritical point disappears.