The energy problem of weak anchoring nematic liquid crystal (NLC) cell is investigated. For given system, there are four solutions satisfying mechanical equilibrium conditions simultaneity under certain condition. Liquid crystal system exist quanta energy level. The values and sequence of energy levels related to the change of external field and anchoring parameters. The state with the smallest energy is the stable state and the others are metastable states, which are separated by the energy barriers. The Freedericksz transition can be considered as the director slippage through these barriers to the lowest energy level and the first order transition and bistable state result from the existence of the multiple disturbed solutions.