Ge-directed zeolites. Forcefield atomic simulations are used to investigate the location of the Ge atoms and the structure-directing agents (SDAs) in the Ge containing ITQ-17 zeolite (see picture). The Ge atoms are found to locate preferentially at the T1 sites which form double four-ring (D4R) units. A combined theoretical and experimental treatment has allowed us to prove the preferential location of Ge atoms in the double four-member rings of the polymorph C of Beta zeolite, and its corresponding structure-directing effect to be demonstrated.