diff --git a/amino-acid-ligand/findLigandExpoVariants.py b/amino-acid-ligand/findLigandExpoVariants.py
new file mode 100644
index 0000000..f3a3a16
--- /dev/null
+++ b/amino-acid-ligand/findLigandExpoVariants.py
@@ -0,0 +1,50 @@
+import openmm.app as app
+from rdkit import Chem
+from concurrent.futures import ThreadPoolExecutor
+
+from rdkit import RDLogger
+RDLogger.DisableLog('rdApp.*')
+
+elements = set(['B', 'Br', 'C', 'Cl', 'F', 'H', 'I', 'N', 'O', 'P', 'S', 'Si'])
+
+def processLigand(smiles, resid):
+    try:
+        mol = Chem.MolFromSmiles(smiles)
+        mol = Chem.AddHs(mol)
+        from rdkit.Chem.MolStandardize import rdMolStandardize
+        enumerator = rdMolStandardize.TautomerEnumerator()
+        enumerator.SetMaxTautomers(2)
+        results = []
+        for variant in enumerator.Enumerate(mol):
+            results.append(Chem.MolToSmiles(variant))
+        return resid, results
+    except:
+        return None
+
+futures = []
+with ThreadPoolExecutor() as executor:
+    for line in open('Components-smiles-oe.smi'):
+        smiles, resid, name = line.split('\t')
+        resid = resid.upper()
+        if resid in app.PDBFile._standardResidues:
+            continue
+        mol = Chem.MolFromSmiles(smiles)
+        if mol is None:
+            continue
+        if any(a.GetSymbol() not in elements for a in mol.GetAtoms()):
+            continue
+        mol = Chem.AddHs(mol)
+        if any(a.GetNumRadicalElectrons() != 0 or a.GetIsotope() != 0 for a in mol.GetAtoms()):
+            continue
+        if mol.GetNumAtoms() < 3 or mol.GetNumAtoms() > 100:
+            continue
+        futures.append(executor.submit(processLigand, smiles, resid))
+
+allSmiles = set()
+with open('ligandExpoVariants.txt', 'w') as output:
+    for future in futures:
+        resid, variants = future.result()
+        for i, smiles in enumerate(variants):
+            if smiles not in allSmiles:
+                print(f'{resid} variant {i+1}\t{smiles}', file=output)
+                allSmiles.add(smiles)
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