[gmx-users] Checkpoint files error

[Apramita Chand]

Dear All,
After equilibration, I want to pass on the checkpoint files state.cpt  for
production run for which I give the command
g_mdrun -s md.tpr -c md.gro -o md.trr -cpi state.cpt -cpo state_md.cpt

The job terminates with error that output files for checkpoint files are
insufficient
Just 1 out of 3files are present
Required: npt.trr ,npt.edr

I have the above mentioned files in the folder ,still the error message
exists

What is the correct procedure to pass checkpoint files?
Also,for generation of tpr file,we use .gro files from the last run.what
are the advantages of using .cpt files? Are they essential?

Thanks in advance for your suggestions

Yours sincerely
Apramita