[gmx-users] Does Non-Protein include SOL?

[Irem Altan]

Hi,

I am simulating a box of TIP4P water (NVT). For the temperature coupling I have the following:

; Temperature coupling is on
tcoupl          = V-rescale     ; modified Berendsen thermostat
tc-grps         = SOL   ; two coupling groups - more accurate
tau_t           = 0.1     ; time constant, in ps
ref_t           = 277     ; reference temperature, one for each group, in K

When I set tc-grps to Non-Protein, GROMACS complains that such a group does not exist. I’d have thought Non-Protein would include SOL. What does Non-Protein refer to exactly?

Best,
Irem