def METHOD_NAME(self, fast_copy=False):
    """Clone this AtomType, faster alternative to deepcopying."""
    return AtomType(
        name=str(self.name),
        tags=self.tags,
        expression=None,
        parameters=None,
        independent_variables=None,
        potential_expression=self.potential_expression_.METHOD_NAME(fast_copy),
        mass=u.unyt_quantity(self.mass_.value, self.mass_.units),
        charge=u.unyt_quantity(self.charge_.value, self.charge_.units),
        atomclass=self.atomclass_,
        doi=self.doi_,
        overrides=set(o for o in self.overrides_)
        if self.overrides_
        else None,
        description=self.description_,
        definition=self.definition_,
    )