How to calculate interfacial properties of a water-TCE system from the last 5ns of 20 ns MD run?

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Dear GROMACS users,

I am currently working on calculating physical properties such as interfacial tension (γ), interfacial thickness (d), and diffusion constant (D) for a water-TCE system containing 288 TCE molecules and 1491 water molecules. I have conducted a 20 ns MD simulation, and its successfully finished. Now I am interested in analyzing the properties of the last 5 ns of this simulation.

To calculate interfacial properties like interfacial tension, we typically require an .edr file (gmx energy -f file.edr command). I have the .edr file for the entire 20 ns MD run. However, I couldn’t generate an .edr file specifically for the last 5 ns. Instead, I have only generated a trajectory file (.xtc) using the trjconv command for the last 5 ns of the simulation.

My question is, can I calculate the interfacial properties for a specific time period using the trajectory (.xtc) file? Is it possible to perform the calculation directly using the trajectory file, or do I need to generate a separate .edr file for this purpose?

Any guidance or assistance on this matter would be greatly appreciated.

Thank you for your help.

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Dear @aish.warya_2024 ,

take a look at the flag -b of the various tools, which gives you control over the starting point of the analysis, e.g. gmx energy -f file.edr -b 15000 should start analysing the file.edr file from 15000ps (15ns).

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yes its working!! Thank you @obZehn for your assistance…