Keyword to defines MOLECULES. After this line, their is one line per molecules with the unit numer and the molecule type like : 1 WAT except if MOLTYPE is used (see below). This keyword should appear in the input file at the very end. The running directory should contain a file named MOLECULES with for each molecule type a line like WAT NAT=3 (3 letters for the molecule name and the number of atoms). The NAT next lines are standard atom name plus xyz inputs (C 0.071715 0.071715 0.000000).
all units are of the same type of molecule defined after MOLTYPE=