The representation consists of a topology, a metal cluster as categorical variables, and an organic linker represented by the SELFIES string. Thus the state S can be expressed as S(topology, metalcluster, organiclinker). Given the maximum length of a SELFIES string, including padding, is 100, the maximum length of T is 102. At each step t, (0 < t < T ), the generator takes state s 1:t in previous steps as inputs and then determines probability distribution p of state s t . At t = 0 and t = 1, the generator respectively determines topologies and metal clusters that are categorical variables. Then, it generates sequences of SELFIES for organic linker during 1 < t ≤ T .