  We study the relationship between Onsager's molecular theory and the
Oseen-Frank theory for nematic liquid crystals. Under the molecular setting, we
consider the free energy that includes the effects of nonlocal molecular
interactions. By imposing the strong anchoring boundary condition on the second
moment of the number density function, we prove the existence of global
minimizers for the free energy. Moreover, when the re-scaled interaction
distance tends to zero, the corresponding global minimizers will converge to a
uniaxial distribution whose orientation is described by a minimizer of
Oseen-Frank energy.
