code: public static boolean hasCrystalCoordinates(IAtomContainer container) {
          Iterator<IAtom> atoms = container.atoms().iterator();
          while (atoms.hasNext()) {
              if (atoms.next().getFractionalPoint3d() == null) {
                  return false;
              }
          }
          return true;
      }
docs: Determines if this model contains fractional (crystal) coordinates.
  
  @return  boolean indication that 3D coordinates are available