private BitSet getUnitCellSet() {
		BitSet bsCell = new BitSet();
		UnitCell unitcell = viewer.getCurrentUnitCell();
		if (unitcell == null)
			return bsCell;
		Point3f cell = new Point3f(unitcell.getFractionalOffset());
		cell.x += 1;
		cell.y += 1;
		cell.z += 1;
		for (int i = atomCount; --i >= 0;)
			if (atoms[i].isInLatticeCell(cell))
				bsCell.set(i);
		return bsCell;
	}