}
public void clearBioPolymers(Group[] groups, int groupCount,
BitSet alreadyDefined) {
for (int i = 0; i < groupCount; ++i) {
Group group = groups[i];
if (group instanceof Monomer) {
Monomer monomer = (Monomer) group;
if (monomer.getBioPolymer() != null
&& (alreadyDefined == null || !alreadyDefined.get(monomer.getModelIndex())))
monomer.setBioPolymer(null, -1);