A molecular dynamics setup can be almost ready—and still need one parameter changed. The challenge is making that adjustment without losing track of what was changed, accidentally overriding another value, or reusing settings that belong to a different simulation step.
In SAMSON’s GROMACS Wizard, you can review and customize parameters for energy minimization, NVT equilibration, NPT equilibration, and production molecular dynamics. The key is to make changes in the right place and check which values take priority.
Start with the step you intend to run
Open the GROMACS Wizard step you actually want to perform. Each step has its own set of available parameters, so an MDP file is preferably matched to that same step. Unless you have a specific simulation reason to change a setting, keep the defaults. This makes the customization focused: you can address the requirement at hand without changing settings just because they are available.
The step tabs expose commonly adjusted settings. To inspect the full parameter editor, click All….
Find the setting—and understand overrides
In the advanced parameter window, settings are grouped in a way that follows the GROMACS MDP parameter documentation. The available groups differ across minimization, equilibration, and production steps. If a parameter’s purpose is unclear, hover over it to see its tooltip, then consult the GROMACS documentation for further explanation.
One detail is especially useful when troubleshooting: Additional Parameters takes priority over overlapping values elsewhere in the interface. If a setting is missing from the editor, add it there. If the same setting is also present in a visible group, the value in Additional Parameters wins. When results do not reflect a value you expected, check for a duplicate entry there.
Reuse an MDP file with a quick review
If you already have an MDP file from a validated workflow, click Load from file… and select it. Prefer a file intended for the same simulation step. Parameters in the file that are not represented in the advanced parameter groups are added to Additional Parameters, where you can review or edit them. You can also paste MDP parameters into that section; pasted values override matching settings in the grouped editor.
Loading a file is a convenient starting point, not a reason to skip review. Check the settings that matter to your run, look for values in Additional Parameters that may take precedence, and use View as text to inspect the complete parameter set in one place. You can save the parameters as an MDP file with Save as…, which is useful when you want a file copy of the settings.
Apply deliberately, and know what Cancel does
Click OK to apply your modifications. Click Cancel to discard parameter modifications made in the editor—with one important exception: resets to default parameters are not discarded by Cancel. Use Reset when you want to restore default values. Modified parameters are saved when SAMSON closes, so they will be available the next time you open it.
A practical final check is to confirm the simulation step, review the full text view, and verify any overlapping entries in Additional Parameters before running the calculation. MDP files used for simulations can also be found in the simulation results folder.
For the full walkthrough, see the GROMACS Wizard guide to applying custom parameters.
Note: SAMSON and all SAMSON Extensions are free for non-commercial use. Get SAMSON.