A production molecular dynamics run is the stage where a prepared, equilibrated system starts generating the trajectory you want to inspect and analyze. It is also an easy place to lose time: choosing the wrong starting file, carrying over inconsistent coupling settings, or launching a run without a clear plan for its outputs can mean repeating work.
A useful way to reduce those risks is to treat production MD as a short sequence of checks: confirm the starting point, review the parameters that matter, choose where the job will run, and decide how you will handle the results.
1. Start from the equilibrated system
Production should follow successful NPT equilibration, with temperature and density stable. In GROMACS Wizard, the input can be either a GRO file from equilibration or an earlier production run, or a batch project from one of those steps. If you are continuing directly from the previous successful run, the auto-fill control can populate the input path for you. Otherwise, select the intended GRO file yourself.
This simple check helps prevent a common workflow mistake: simulating from a structure that is not the one you just equilibrated. Before continuing, verify that the chosen input represents the system you actually want to study.
2. Review parameters with continuity in mind
The Parameters section exposes frequently adjusted settings, including the integration time step and number of steps. Additional GROMACS options are available through All…. Defaults are provided for typical production runs, but a default is not a substitute for checking whether the settings suit your particular system and scientific question.
Two continuity checks are especially important in the workflow:
- Make sure the temperature coupling settings correspond to those used for NVT equilibration. If velocity generation is enabled, check its temperature too.
- Make sure the pressure coupling settings correspond to those used for NPT equilibration.
Position-restraint options (POSRES*) are filled automatically based on the input system. If you need to reset advanced settings, load parameters from an MDP file, or save them for reuse, the Advanced parameters window provides those controls. Modified parameters are saved when SAMSON closes, so take care when opening a later project: previously saved settings may still be present.
For the tutorial exercise, the maximum number of steps is set to 50,000 so the run finishes quickly. Treat that as a tutorial setting, not a universal production-run recommendation; choose run length and other parameters for your own study.
3. Choose where the computation should run
GROMACS Wizard offers three paths. Generate inputs creates a project you can run elsewhere, such as on a cluster. Simulate locally uses the GROMACS version shipped with SAMSON or one configured in settings. Simulate in the cloud can be useful when a system needs more resources than your local computer has available; cloud computation requires credits.
For a local run, progress appears in the Output window, and the Local jobs control lets you check job status. This makes it possible to keep using SAMSON while calculations are running. If you submit multiple jobs or a batch job, check their state there rather than expecting a single completion prompt.
4. Plan the results workflow before the job finishes
When results are imported, dialogs let you choose trajectory handling, including whether to import the whole trajectory, only the last frame, or a selected range. You can also choose periodic-boundary-condition treatment and what to center the system on, such as the protein. If you cancel trajectory import, the result files are not deleted and the plots can still be generated.
After the job finishes and results are loaded, GROMACS Wizard generates plots for radius of gyration and RMSD. These are useful views of the run, but they answer different questions: radius of gyration tracks the system’s compactness, while RMSD reports structural deviation relative to the selected reference. Neither plot alone establishes that a simulation is scientifically valid; interpret them alongside your system, settings, and analysis goals. Pulling simulations also produce plots for pull force and coordinates.
Results are stored in the configured results folder, in a directory named with the launch date and time and a step suffix; production MD uses _md. Keeping track of this location makes it easier to find the files for analysis or follow-up simulations.
For the complete walkthrough, see the GROMACS Wizard production MD tutorial.
Note: SAMSON and all SAMSON Extensions are free for non-commercial use. Get SAMSON.