def get_rotatable_bonds(self,mol):
		"""Determines rotatable bonds in a ligand molecule
		Takes:
			* mol * - mol file in rdkit environment
		Output:
			* bonds * - tuples of atom ids
		"""
		RotatableBondSmarts = Chem.MolFromSmarts('[!$(*#*)&!D1]-&!@[!$(*#*)&!D1]')
		bonds = mol.GetSubstructMatches(RotatableBondSmarts,uniquify=1)
		return bonds