def METHOD_NAME(self):
    if not os.path.exists(self.datapath):
        property_unit_dict = {OrganicMaterialsDatabase.BandGap: "eV"}
        dataset = create_dataset(
            datapath=self.datapath,
            format=self.format,
            distance_unit="Ang",
            property_unit_dict=property_unit_dict,
        )
        self._convert(dataset)
    else:
        dataset = load_dataset(self.datapath, self.format)