code: @Override
  	public boolean isCrystallographic() {
  		if (pdbHeader.getExperimentalTechniques()!=null) {
  			return ExperimentalTechnique.isCrystallographic(pdbHeader.getExperimentalTechniques());
  		} else {
  			// no experimental technique known, we try to guess...
  			if (pdbHeader.getCrystallographicInfo().getSpaceGroup()!=null) {
  				// space group defined but no crystal cell: incomplete info, return false
  				return  pdbHeader.getCrystallographicInfo().getCrystalCell() != null &&
  						pdbHeader.getCrystallographicInfo().getCrystalCell().isCellReasonable();
  			}
  		}
  		return false;
  	}
docs: Whether this Structure is a crystallographic structure or not.
  It will first check the experimental technique and if not present it will try
  to guess from the presence of a space group and sensible cell parameters
  
  @return true if crystallographic, false otherwise