void deleteBonds(BitSet bs) {
		int iSrc = 0;
		int iDst = 0;
		for (; iSrc < bondCount; ++iSrc) {
			Bond bond = bonds[iSrc];
			if (!bs.get(iSrc))
				bonds[iDst++] = bond;
			else bond.deleteAtomReferences();
		}
		for (int i = bondCount; --i >= iDst;)
			bonds[i] = null;
		bondCount = iDst;
	}