Large bipolarons in two and three dimensions

The large bipolaron in two and three dimensions is investigated by combinin g the reasonable asymptotic relative wavefunctions and the Lee-Low-Pines-Hu ybrechts (LLP-H) variational method. The values of the critical coupling co nstant ct, above which bipolarons may exist and the critical ratio of diele ctric constants eta(c) below which bipolarons may exist are evaluated, whic h are very close to the recent results obtained within totally different va riational approaches. It is also found that low-dimensional materials are m ore favorable for the formation of bipolarons.