1/viscosity output is wrong in gmx-2018.2, but OK in gmx-5.1.5
When calculating viscosity with periodic perturbation, the output average value of 1/viscosity in 2018.2 is around zero. The NEMD is set up in NVT ensemble. Only "cos-acceleration" is set, instead of "acc-grps" and "acceleration" in .mdp file. The same tpr file works with gmx-5.1.5, i.e. gives value in reasonable range.
Both versions of gromacs are compiled on CentOS 7, with gcc-7.3.1/or gcc-4.8.5, cuda-9.2, with the following cmake command:
cmake .. -DGMX_BUILD_OWN_FFTW=ON -DGMX_GPU=on