# Run-time control¶

The progress of the force-field optimization can be controlled by changing parameters in the istop file present in the calculation directory. The file is read every 10 iterations. The parameters are explained below:

• StopKey - replace 0 with 1 to stop the calculation
• Beta - the current $$\beta$$ value corresponding to the mcbeta control parameter
• Command - one of: NONE, WALK, JUMPWALK, MINIMIZE, JUMPMINI:
• NONE - no change in the procedure
• WALK - switch to Monte-Carlo steps (the default);
• MINIMIZE - switch to gradient-free minimization of the latest accepted force-field;
• JUMPWALK - take the best force-field so far and start the Monte-Carlo procedure from there;
• JUMPMINI - take the best force-field so far and minimize it.
• ScaleFactor - change the current step size corresponding to the mcstep control parameter
• ActiveParameterFraction - set the fraction of force-field parameters changed at each step (mcacpf)
• deltaBeta - change the current value of the mcdbet control parameter
• BetaScaling - change the current value of the mcbsca control parameter
• ScaleParSpace - change the current value of the mcscps control parameter