On 4/5/16 9:34 AM, Brett wrote:
Dear Justin,

Suppose at the end of NVT equilibation and before the start of the following 
NPT equilibation, I intentionally (or by accident) delete the nvt_prev.cpt file 
from the directory, does it affect the run of the  NPT equilibation step?


No. Once an input .tpr file has been constructed, deletion of any previous files is irrelevant (not that it's necessarily good practice). Going by your sequence of commands below, nvt_prev.cpt wasn't used for anything, anyway. But as I said, *_prev.cpt files are just a fail safe, they're usually not needed for anything but corner cases in which a corrupt or incomplete .cpt is written.

-Justin

Brett









At 2016-04-05 21:27:41, "Justin Lemkul" <jalem...@vt.edu> wrote:


On 4/5/16 9:24 AM, Brett wrote:
Dear All,

Based on the on-line Lysozyme tutorial, I started a MD from energy
minimization to NVT equlibation to NPT equlibration, and I am now in the
production MD step.

When I checked my Directory containing all the MD files for the whole MD
process, I find there is a "mdout.mdp". Is my understanding correct on that,
in the energy minimization step, it will create a "mdout.mdp" file, and in
any of the following of NVT equlibation, NPT equlibration and production MD
step, a "mdout.mdp" file will be created and automatically replaced the
"mdout.mdp" file created in the previous step?


GROMACS backs up files, it doesn't replace them unless you set GMX_MAXBACKUP=-1.

As I mentioned, currently I was in the production M step, and if I
intentionally delete the "mdout.mdp" file from the Directory, how does it
affect my production MD?


mdout.mdp is just to record your options for posterity.  Deleting it has no
effect on anything.

The next question, during my production MD step, I checked my Directory, and
here let me take the NVT related files as example, I found there were a
nvt.cpt and a nvt_prev.cpt file. Suppose my NVT equilibration step lasts for
100 ps, is the nvt.cpt the file created by "gmx grompp -f npt.mdp -c nvt.gro
-t nvt.cpt -p topol.top -o npt.tpr", and the nvt_prev.cpt the cpt file
created at the end of "gmx mdrun -deffnm npt -v &", and this nvt_prev.cpt
file will be used at the beginning of the next step NPT equilibration?


Look at the time stamps.  Checkpoint files are mdrun output and are written per
the mdrun command line -cpt option, which defaults to once every 15 minutes.  A
previous checkpoint (*_prev.cpt) is written as a failsafe, in case something
goes wrong writing the current checkpoint so you don't lose all your work in the
event of a disruption.

-Justin

--
==================================================

Justin A. Lemkul, Ph.D.
Ruth L. Kirschstein NRSA Postdoctoral Fellow

Department of Pharmaceutical Sciences
School of Pharmacy
Health Sciences Facility II, Room 629
University of Maryland, Baltimore
20 Penn St.
Baltimore, MD 21201

jalem...@outerbanks.umaryland.edu | (410) 706-7441
http://mackerell.umaryland.edu/~jalemkul

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Justin A. Lemkul, Ph.D.
Ruth L. Kirschstein NRSA Postdoctoral Fellow

Department of Pharmaceutical Sciences
School of Pharmacy
Health Sciences Facility II, Room 629
University of Maryland, Baltimore
20 Penn St.
Baltimore, MD 21201

jalem...@outerbanks.umaryland.edu | (410) 706-7441
http://mackerell.umaryland.edu/~jalemkul

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