Add alternative online tools for molecular orbitals when Psi4 is unavailable

app.py

@@ -118,6 +118,28 @@ def smiles_to_molecular_orbitals(smiles_input: str, name_input: str) -> str:
             "<p><strong>Molecular orbital rendering requires Psikit + Psi4.</strong> "
             "Install them locally with <code>pip install psikit psi4 py3Dmol</code> "
             "and run this app on your machine.</p>"
+            "<p><strong>Alternative online tools:</strong></p>"
+            "<ul>"
+            "<li><a href='https://www.webmo.net/' target='_blank'>WebMO</a> - Web-based molecular modeling</li>"
+            "<li><a href='https://gaussian.com/' target='_blank'>Gaussian</a> - Quantum chemistry software</li>"
+            "<li><a href='https://www.chemcraftprog.com/' target='_blank'>ChemCraft</a> - Molecular visualization</li>"
+            "</ul>"
+            f"<p>You can copy this SMILES to these tools: <code>{canonical_smiles}</code></p>"
+        )
+
+    try:
+        import psi4  # Check if psi4 is available
+    except ImportError:
+        return (
+            "<p><strong>Psi4 is not available on this platform.</strong> "
+            "Molecular orbital calculations require Psi4, which is not supported on Hugging Face Spaces.</p>"
+            "<p><strong>Alternative online tools:</strong></p>"
+            "<ul>"
+            "<li><a href='https://www.webmo.net/' target='_blank'>WebMO</a> - Web-based molecular modeling</li>"
+            "<li><a href='https://gaussian.com/' target='_blank'>Gaussian</a> - Quantum chemistry software</li>"
+            "<li><a href='https://www.chemcraftprog.com/' target='_blank'>ChemCraft</a> - Molecular visualization</li>"
+            "</ul>"
+            f"<p>You can copy this SMILES to these tools: <code>{canonical_smiles}</code></p>"
         )
 
     try: