Extending simulation which has simulated annealing

GROMACS version: 2020.4
GROMACS modification: No


I have to do a simulation which in which I have to change the temperature of the system. I have included this in my mdp file:

; Temperature coupling is on
tcoupl                  = nose-hoover           ; modified Berendsen thermostat
tc-grps                 = system                ; two coupling groups - more accurate
tau_t                   = 0.4                   ; time constant, in ps
ref_t                   = 240                   ; reference temperature, one for each group, in K

; Simulated Annealing
annealing               = single
annealing-npoints       = 2
annealing-temp          = 240 80                ; temperature decreases from 240 to 80
annealing-time          = 0 2000                ; temperatre decreases from 240K at time = 0 ps to 90K at time = 2000 ps (2 ns)

My simulation that I am going to run is with a much lower cooling rate and can go as long as or even longer than 1.6 microseconds.

My question is if at all due to walltime limitations I cannot finish my simulation and I have to continue it, do I have to change the mdp file’s simulated annealing section or will gromacs take care of it it self when I just use convert-tpr to change the tpr file using the state.cpt file?

If I have to change what is the easiest way to find how to find the new initial temperature?

One more query I have is, if a 20 ns simulation takes say 4 hrs, will a 100ns simulation of the same system take 20hrs? Like does it scale linearly or not?

Awaiting your response.

Thank you.