A JSON serializable dict representation of self.

def as_dict(self):
        """
        A JSON serializable dict representation of self.
        """
        return {"@module": self.__class__.__module__,
                "@class": self.__class__.__name__,
                "operation": self.operation, "title": self.title,
                "xc": self.xc.as_dict(), "basis_set": self.basis_set.as_dict(),
                "units": self.units.as_dict(), "scf": self.scf.as_dict(),
                "geo": self.geo.as_dict(),
                "others": [k.as_dict() for k in self.other_directives]}