Backport fix from #485 into main. [ci skip]

Author: lohedges

python/BioSimSpace/_Config/_gromacs.py

@@ -186,8 +186,11 @@ def createConfig(self, version=None, extra_options={}, extra_lines=[]):
                         protocol_dict["pcoupl"] = "c-rescale"
                     else:
                         protocol_dict["pcoupl"] = "berendsen"
-                    # 1ps time constant for pressure coupling.
-                    protocol_dict["tau-p"] = 1
+                    # Do the MC move every 100 steps to be the same as AMBER.
+                    protocol_dict["nstpcouple"] = 100
+                    # 4ps time constant for pressure coupling. The tau-p has to be
+                    # 10 times larger than nstpcouple * dt (4 fs)
+                    protocol_dict["tau-p"] = 4
                     # Pressure in bar.
                     protocol_dict["ref-p"] = (
                         f"{self._protocol.getPressure().bar().value():.5f}"