code: private void setAtomsToPlace(IAtomContainer ac) {
          for (int i = 0; i < ac.getAtomCount(); i++) {
              ac.getAtom(i).setFlag(CDKConstants.ISPLACED, true);
          }
      }
docs: Sets the atomsToPlace attribute of the ModelBuilder3D object.
  
  @param  ac  The new atomsToPlace value