def stoichiometry( self ):
        """
        Stoichiometry for this POSCAR, as a Counter.
        e.g. AB_2O_4 -> Counter( { 'A': 1, 'B': 2, O: 4 } )
        
        Args:
            None

        Returns:
            None
        """
        return Counter( { label: number for label, number in zip( self.atoms, self.atom_numbers ) } )
Stoichiometry for this POSCAR, as a Counter.
        e.g. AB_2O_4 -> Counter( { 'A': 1, 'B': 2, O: 4 } )
        
        Args:
            None

        Returns:
            None