if (rGroupQuery==null || rGroupQuery.getRootStructure() == null || rGroupQuery.getRootStructure().getAtomCount()==0)
throw new CDKException( "The R-group is empty");
IAtomContainerSet moleculeSet = chemModel.getBuilder().newInstance(IAtomContainerSet.class);
moleculeSet.addAtomContainer(rGroupQuery.getRootStructure());
chemModel.setMoleculeSet(moleculeSet);
for (int rgrpNum : sortRGroupNumbers()) {
RGroupList rgrpList = rGroupQuery.getRGroupDefinitions().get(rgrpNum);
for (RGroup rgrp : rgrpList.getRGroups()) {
chemModel.getMoleculeSet().addAtomContainer(rgrp.getGroup());