Abstract
For the first time reentrances below smectic A1 are obtained with the molecular "spin-gas" model of liquid crystals, in agreement with recent experiments. The model further predicts sextuple (and octuple) reentrance, nematicsmecticAdnematicsmecticAdnematicsmecticA1nematicsmecticAd(nematicsmecticA1), as temperature is lowered. Two distinct reentrance mechanisms are found: microscopic frustration of dipoles and competing short-range orders.