# Analysis with .trr
**URL:** https://gromacs.bioexcel.eu/t/analysis-with-trr/7852
**Category:** User discussions
**Created:** [December 13, 2023, 4:40pm UTC](https://gromacs.bioexcel.eu/t/analysis-with-trr/7852 "2023-12-13T16:40:33Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@Rochik](https://gromacs.bioexcel.eu/u/Rochik)
#### Post date: [December 13, 2023, 4:40pm UTC](https://gromacs.bioexcel.eu/t/analysis-with-trr/7852/1 "2023-12-13T16:40:33Z")
Dear Experts,
I have a question regarding the use of the .trr trajectory files. Could you please let me know what kind of analysis we can do by using this file which is not possible by “xtc”? I need an example of such an analysis. (I know the difference between trr and xtc files.)
Thank you so much
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### Author:  [@yehon](https://gromacs.bioexcel.eu/u/yehon)
#### Post date: [December 16, 2023, 12:56pm UTC](https://gromacs.bioexcel.eu/t/analysis-with-trr/7852/2 "2023-12-16T12:56:38Z")
Hello Rochik,
Here are some of the common analyses, listed in order of what I believe to be more important:
- _gmx dos_ - useful for calculating a more reliable heat capacity for solvents, by utilizing the velocity correlation information found in `.trr` files.
- _gmx tcaf_ - method to detemine the viscosity (also use the velocity correlation).
- _gromacs LS_ - calculating local stress or lateral pressure within your system.
- _gmx make\_edi/nmens_ - essential dynamics/normal mode analysis.
Beside those, I’m sure that there are more complex analyses that may also require the trr files.
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### Author:  [@Rochik](https://gromacs.bioexcel.eu/u/Rochik)
#### Post date: [December 18, 2023, 9:38am UTC](https://gromacs.bioexcel.eu/t/analysis-with-trr/7852/3 "2023-12-18T09:38:59Z")
Thank you so much for your useful information.