[gmx-users] Gromacs 4.0.4 problem in extending MARTINI run by 600 ns, but no problem extending run by 60 ns using tpbconv

[Mark Abraham]

himanshu khandelia wrote:
> Dear All,
> 
> I have run into this problem while using tpbconv. I typically write a 
> new set of output files every ~ 600 ns. However, after about 108 
> repeats, tpbconv fails to write a new .tpr file:
> 
> ###################
> tpbconv -s poptocg25-108.tpr -extend 600000 -o poptocg25-109.tpr
> 
> ...
> ...
> Reading toplogy and shit from poptocg25-108.tpr
> Reading file poptocg25-108.tpr, VERSION 4.0.4 (single precision)
> Extending remaining runtime of by 600000 ps (now -2134967296 steps)

There's the problem. The variable that counts the number of steps is 
signed, and has overflowed. It seems even a "long" variable is not 
enough for CG simulations :-) Please post a bugzilla and it will get 
fixed for the next version.

Meantime, you can work around the situation by building a new .tpr that 
continues from your last endpoint.

Mark

> You've simulated long enough. Not writing tpr file
> ###################
> 
> However, there is no problem if I try to extend the run by only 60 ns?
> 
> ###################
> tpbconv -s poptocg25-108.tpr -extend 600000 -o poptocg25-109.tpr
> 
> ...
> ...
> 
> Reading toplogy and shit from poptocg25-108.tpr
> Reading file poptocg25-108.tpr, VERSION 4.0.4 (single precision)
> Extending remaining runtime of by 60000 ps (now 2142000000 steps)
> Writing statusfile with starting step          0 and length 2142000000 
> steps...
> time      0.000 and length 64260000.000 ps
> ###################
> 
> Thank you for the help,
> 
> -himanshu
> 
> 
> ------------------------------------------------------------------------
> 
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