free energy dhdl differs between gmx2020 and gmx2021
Running a small test case of a relative free energy calculation for a ligand in water with gmx2020 and gmx2021 gives different dhdl values already for the first steps (potential and kinetic energies are equal for the two gromacs versions). The difference in dhdl also remains when running in double precision. In turn, the final calculated free energies show significant differences between gmx2020 and gmx2021.
Attached is the test example. README file in the folder describes the input files.test_dG.tar.gz