code: private static Group[] rChainAfp(FatCatParameters params, AFPChain afpChain, Atom[] ca1, Atom[] ca2) throws StructureException{
  		params.setMaxTra(0);
  		afpChain.setMaxTra(0);
  		return chainAfp(params,afpChain,ca1,ca2);
  	}
docs: runs rigid chaining process