# How could someone get the entropic and enthalpic contributions of a free energy calculation?

**URL:** <https://gromacs.bioexcel.eu/t/how-could-someone-get-the-entropic-and-enthalpic-contributions-of-a-free-energy-calculation/3721>\
**Category:** User discussions\
**Tags:** analysis-tools\
**Created:** [February 22, 2022, 5:44am UTC](https://gromacs.bioexcel.eu/t/how-could-someone-get-the-entropic-and-enthalpic-contributions-of-a-free-energy-calculation/3721 "2022-02-22T05:44:45Z")\
**Posts on this page:** 2\
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**Author:** ![ehsan](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/ehsan/32/1345_2.png) [@ehsan](https://gromacs.bioexcel.eu/u/ehsan)\
**Post date:** [February 22, 2022, 5:44am UTC](https://gromacs.bioexcel.eu/t/how-could-someone-get-the-entropic-and-enthalpic-contributions-of-a-free-energy-calculation/3721/1 "2022-02-22T05:44:45Z")

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GROMACS version: 2021.2  
GROMACS modification: No  
Hi all,

I did a solvation free energy calculation (with BAR method) and now I want to get the entropic and enthalpic contributions of the free energy, how could I do that with GROMACS?

Thanks

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<div class="post-metadata">

**Author:** ![ehsan](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/ehsan/32/1345_2.png) [@ehsan](https://gromacs.bioexcel.eu/u/ehsan)\
**Post date:** [February 27, 2022, 9:19pm UTC](https://gromacs.bioexcel.eu/t/how-could-someone-get-the-entropic-and-enthalpic-contributions-of-a-free-energy-calculation/3721/2 "2022-02-27T21:19:28Z")

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For calculating the enthalpy of solvation, can we easily run three simulations: “solution (solvent + solute)” + “vacuum for solute” + “solvent alone” and get the solvation enthalpy as follow?

ΔH (solvation) = **(H\_solution)** – ( **H\_solute** \*-in-vaccum\*) – ( **H\_solvent** \*-alone\*)