The threshold simulations reveal a dual-funneled energy landscape with deep basins centred on polymorphs I and II (Fig. ). Polymorph I is the lowest energy structure in its Figure : Disconnectivity graph from threshold simulations for the 1:1 nicotinamide:benzoic acid co-crystal in space group P 2 1 /c. funnel (left of Fig. ), while one lower energy structure is located in the funnel containing II (right of Fig. ). Several lower energy structures are located by CSP in space group P 2 1 /c, but not sampled during the threshold simulations; these structures might lie outside of the two funnels, where little sampling has been performed. A complete picture of the energy landscape would require threshold sampling from some of the unobserved polymorphs as well as I and II.