Setting update frequency to 0 disables MonteCarloBarostat

openmmapi/include/openmm/MonteCarloBarostat.h

@@ -75,13 +75,15 @@ public:
         return defaultPressure;
     }
     /**
-     * Get the frequency (in time steps) at which Monte Carlo pressure changes should be attempted.
+     * Get the frequency (in time steps) at which Monte Carlo pressure changes should be attempted.  If this is set to
+     * 0, the barostat is disabled.
      */
     int getFrequency() const {
         return frequency;
     }
     /**
-     * Set the frequency (in time steps) at which Monte Carlo pressure changes should be attempted.
+     * Set the frequency (in time steps) at which Monte Carlo pressure changes should be attempted.  If this is set to
+     * 0, the barostat is disabled.
      */
     void setFrequency(int freq) {
         frequency = freq;

openmmapi/src/MonteCarloBarostatImpl.cpp

@@ -61,7 +61,7 @@ void MonteCarloBarostatImpl::initialize(ContextImpl& context) {
 }
 
 void MonteCarloBarostatImpl::updateContextState(ContextImpl& context) {
-    if (++step < owner.getFrequency())
+    if (++step < owner.getFrequency() || owner.getFrequency() == 0)
         return;
     step = 0;