:sup:`189` Laino T., Mohamed F., Laio A. and Parrinello M.,
"An Efficient Real Space Multigrid QM/MM Electrostatic Coupling", *J. Chem. Theory Comput.*, **1**, 1176 (2005).
+.. raw:: html
+
+ </div>
+
+.. raw:: html
+
+ <div id="ref-Gapsys2012">
+
+.. _refGapsys2012:
+
+:sup:`185` V. Gapsys, D. Seeliger, and B.L. de Groot,
+"New Soft-Core Potential Function for Molecular Dynamics Based Alchemical Free Energy Calculations", *J. Chem. Theor. Comput.*, **8** 2373-2382 (2012).
+
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</div>