[gmx-users] Continuing simulation with velocities and positions of equilibrated run and after modifying .mdp

[Bappa Ghosh]

Hello All,

I have a  polymer chain of N=50. I equilibrate (NVT) the polymer for nsteps
= 50000 at T= 295K keeping only the N=1 positional restrained  .
After finishing the equilibration run, the production run is to be started
lifting the positional restrain and applying a pull force on N=1 along
Z-direction.

My questions
(A) Can I use the state.cpt file of the completed equilibration run to
start my production from the same velocities and positions ?
In this case, I have to modify .mdp file in two places for production run-
(1) to lift the positional restrain on N=1 , I need to remove "define =
-DPOSRES_N1".
(2) to apply the pull force on N=1 ,     pull= constant_force
                                                               pull_group1=
N1
                                                               pull_dim= N
N Y
                                                               pull_k1 = 5

(B) Is there a way to check that I am starting  from the same velocities
and positions  of the last equilibration frame ?
I am using GROMACS-4.5.5 (single precision).

Thank you in advance.

Best regards,
Bappa Ghosh