Checks that ionic step convergence has been reached, i.e. that vasp
        exited before reaching the max ionic steps for a relaxation run

def converged_ionic(self):
        """
        Checks that ionic step convergence has been reached, i.e. that vasp
        exited before reaching the max ionic steps for a relaxation run
        """
        nsw = self.parameters.get("NSW", 0)
        return nsw <= 1 or len(self.ionic_steps) < nsw