Connection between the phenomenological and microscopic approaches in the theory of liquid crystals

Possibility of formulating the theory of liquid crystals on the basis of microscopic conceptions is considered. According to the N.  N. Bogoliubov method, the chain of equations for distribution functions depending on the position and spatial orientation of moleculi is obtained. On the basis of these equations the hydrodynamical equations of the liquid crystal are derived and the correspondence between the equations obtained and the equations used in the phenomenological theory of liquid crystal is established. Explicit form of the elasticity tensor is obtained and a scheme of obtaning the Franck elastic constants in terms of microscopic parameters is outlined.