diff --git a/iMiner/md/amber/renumber_indices.py b/iMiner/md/amber/renumber_indices.py
new file mode 100644
index 0000000..c9800e2
--- /dev/null
+++ b/iMiner/md/amber/renumber_indices.py
@@ -0,0 +1,84 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+'''
+Overall layout of the code:
+    1, We make RDKit Mol objects from the sdf files
+    2, We go through the molecules and see which atoms have the same symbols and positions in all molecules
+    3, We make dictionaries giving the correspondance between old and new coordinates
+    4, We make new conformers where the first n atoms are the same for all molecules
+    5, We write these out to sdf files
+'''
+from rdkit import Chem
+
+def finish_dict(mol, mol_dict, count): 
+    for atom in mol.GetAtoms():
+        k = atom.GetIdx()
+        if k not in mol_dict:
+            mol_dict[k] = count
+            count += 1
+    return mol_dict, count
+
+def make_new_mol(old_mol, mol_dict, count):
+    assert count == len(old_mol.GetAtoms())
+    new_mol = Chem.RWMol()
+    rev_dict = {v:k for k,v in mol_dict.items()}
+    for k in range(count):
+        atom = old_mol.GetAtomWithIdx(rev_dict[k])
+        new_mol.AddAtom(atom)
+    for bond in old_mol.GetBonds():
+        new_begin_idx = mol_dict[bond.GetBeginAtomIdx()]
+        new_end_idx = mol_dict[bond.GetEndAtomIdx()]
+        new_mol.AddBond(new_begin_idx, new_end_idx, bond.GetBondType())
+    conf = old_mol.GetConformer()
+    new_conf = Chem.Conformer(new_mol.GetNumAtoms())
+    for old_idx, new_idx in mol_dict.items():
+        pos = conf.GetAtomPosition(old_idx)
+        new_conf.SetAtomPosition(new_idx, pos)
+    new_mol.AddConformer(new_conf)
+    return new_mol
+
+def similar_coords(conf1, idx1, conf2, idx2, tol=0.01): #test if coordinates are similar to within some tolerance
+    c1, c2 = conf1.GetAtomPosition(idx1), conf2.GetAtomPosition(idx2)
+    if ((c1.x - c2.x)**2 + (c1.y - c2.y)**2 + (c1.z - c2.z)**2)**0.5 <= tol:
+        return True
+    return False
+
+def get_similar_atoms(molA, molB, molC):
+    confA, confB, confC = molA.GetConformer(), molB.GetConformer(), molC.GetConformer()
+    dictA, dictB, dictC = {}, {}, {}
+    counter = 0
+    for A in molA.GetAtoms():
+        idxA = A.GetIdx()
+        for B in molB.GetAtoms():
+            idxB = B.GetIdx()
+            if similar_coords(confA, idxA, confB, idxB) and A.GetSymbol() == B.GetSymbol():
+                for C in molC.GetAtoms():
+                    idxC = C.GetIdx()
+                    if similar_coords(confA, idxA, confC, idxC) and A.GetSymbol() == C.GetSymbol():
+                        dictA[idxA], dictB[idxB], dictC[idxC] = counter, counter, counter
+                        counter += 1
+    return dictA, dictB, dictC, counter
+
+def renumber_indices(molA, molB, molC):
+    dictA, dictB, dictC, counter = get_similar_atoms(molA, molB, molC)
+    counterA, counterB, counterC = counter, counter, counter
+    dictA, counterA = finish_dict(molA, dictA, counterA)
+    dictB, counterB = finish_dict(molB, dictB, counterB)
+    dictC, counterC = finish_dict(molC, dictC, counterC)
+    newmolA = make_new_mol(molA, dictA, counterA)
+    newmolB = make_new_mol(molB, dictB, counterB)
+    newmolC = make_new_mol(molC, dictC, counterC)
+    return newmolA, newmolB, newmolC
+
+if __name__ == '__main__':
+    sdf1 = 'zikv_hel/data/lig_2836_h.sdf'
+    sdf2 = 'zikv_hel/data/lig_2841_h.sdf'
+    sdf_mcs = 'zikv_hel/data/mcs.sdf'
+    
+    mol1 = Chem.SDMolSupplier(sdf1, removeHs=False)[0]
+    mol2 = Chem.SDMolSupplier(sdf2, removeHs=False)[0]
+    mol_mcs = Chem.SDMolSupplier(sdf_mcs, removeHs=False)[0]
+    newmol_mcs, newmol1, newmol2 = renumber_indices(mol_mcs, mol1, mol2)
+    
+    Chem.SDWriter('zikv_hel/data/2836_test.sdf').write(newmol1)
+    Chem.SDWriter('zikv_hel/data/2841_test.sdf').write(newmol2)
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