code: public static Structure removeModels(Structure s) {
  		if (s.nrModels() == 1)
  			return s;
  
  		Structure n = new StructureImpl();
  		// go through whole substructure and clone ...
  
  		// copy structure data
  
  		n.setPDBCode(s.getPDBCode());
  		n.setName(s.getName());
  
  		// TODO: do deep copying of data!
  		n.setPDBHeader(s.getPDBHeader());
  		n.setDBRefs(s.getDBRefs());
  
  		n.setSites(s.getSites());
  
  		n.setChains(s.getModel(0));
  
  		return n;
  
  	}
docs: Remove all models from a Structure and keep only the first
  
  @param s
  original Structure
  @return a structure that contains only the first model
  @since 3.0.5