  We clarify some technical issues in the present generalized
effective-potential Landau theory (GEPLT) that makes the GEPLT more consistent
and complete. Utilizing this clarified GEPLT, we analytically study the quantum
phase transitions of ultracold Bose gases in bipartite superlattices at zero
termparture. The corresponding quantum phase boundaries are analytically
calculated up to the third-order hopping, which are in excellent agreement with
the quantum Monte Carlo (QMC) simulations.
