Conformer exploration for a cluster of weakly interacting flexible molecules is an even more daunting task than for isolated flexible molecules. There are significantly more rotatable bonds in such a cluster than in an individual molecule, and thus exponentially more conformational space to explore. In addition, the molecules are also free to rotate and translate relative to each other, so one must ensure that they remain close enough to each other to interact. A further problem arises if there are directed interactions between the molecules, such as intermolecular hydrogen bonds. In such cases, the low-energy conformations frequently reside in a series of narrow potential wells, which can be quite difficult for an automated procedure to find. Given these challenges, even the best algorithms can struggle to produce a reasonable ensemble.