Water clusters confined in icosahedral fullerene cavities

► We model the interaction energy of water clusters confined in fullerene cavities. ► C60 and C180 are chosen as icosahedral cavities. ► The rigid TIP4P and flexible q-TIP4P/F water-water potentials are used. ► While C60 can confine exothermically only one water molecule, C180 does up to 17. ► New global minimum structures are reported for water clusters inside C180.