We study the extended Bose--Hubbard model describing an ultra-cold gas ofView original: http://arxiv.org/abs/1109.4782
dipolar molecules in an optical lattice, taking into account all on-site and
nearest-neighbor interactions, including occupation-dependent tunneling and
pair tunneling terms. Using exact diagonalization and the multi-scale
entanglement renormalization ansatz (MERA), we show that these terms can
destroy insulating phases and lead to novel quantum phases. These considerable
changes of the phase diagram have to be taken into account in upcoming
experiments with dipolar molecules.