When modeling molecular systems and transitions, understanding and accurately setting up energy evaluation is crucial. If you're using SAMSON's Protein Path Finder app, properly configuring energy evaluation ensures that your conformation pathways are based on physically meaningful states. Here's a step-by-step guide to get this aspect right.
Why Is Energy Evaluation Important?
Energy evaluation helps ensure that the computed conformational transitions between states follow physically plausible energy landscapes. For example, if the energies of conformations along a path are too high, these transitions may be unrealistic. Therefore, setting the interaction model and state updater with proper parameters is essential when using the Protein Path Finder app.
Pre-Minimization: An Essential Step
Note
Your system should already be minimized before setting up energy evaluation. You can minimize the system in SAMSON by navigating to Edit > Minimize. SAMSON employs the Universal Force Field (UFF) for this process.
Step 1: Selecting an Interaction Model and State Updater
In the Settings tab of the Protein Path Finder app, you will need to:
- Choose the interaction model: Select Universal Force Field (UFF) from the drop-down menu.
- Select the state updater: Use the Fast Inertial Relaxation Engine (FIRE).
If you do not see the FIRE state updater in the list, ensure that you have it installed (see the Requirements section).
Step 2: Configuring Parameters
After selecting the interaction model and state updater:
- A window will appear, prompting you to apply the new model. Select Yes.
- When configuring the Universal Force Field model, choose the option to use existing bonds.
Once configured, you will see two additional parameter windows:
- Universal Force Field Properties: Displays UFF parameters and energies of the current system state.
- FIRE Properties: Provides options to set the state updater parameters.
Step 3: Setting FIRE Parameters
Tip
Set the FIRE state updater parameters as follows for optimized results:
- Step size:
1 fs - Number of steps:
1
The Universal Force Field window helps track the energies for any changes in the system's state, giving real-time feedback as you tweak parameters.
What's Next?
With energy evaluation set up, you're ready to define the system, configure the sampling box, and fine-tune search parameters as you progress toward finding transition paths with the Protein Path Finder app.
Accurately setting parameters at this stage ensures reliable results for subsequent analyses. Review energy curves, refine conformation pathways, and export results confidently—all while working on validated energy landscapes.
For further details and the next steps, including system setup and running the planner, refer to the Protein Path Finder Documentation.
Note: SAMSON and all SAMSON Extensions are free for non-commercial use. You can get started by downloading SAMSON from SAMSON Connect.