RE: Negative step number

From: Vermaas, Joshua (Joshua.Vermaas_at_nrel.gov)
Date: Sat Apr 28 2018 - 23:07:17 CDT

You are running into a 32-bit overflow problem. For 32-bit integers, 2^31 is the largest representable number. Set "firsttimestep 0" in your config file. It'll give you another 2 billion steps of MD before you need to worry about it again. At some point there were rumblings of switching many of the counters over to 64-bit, but I don't know if that has happened yet. It certainly hadn't happened in NAMD 2.10.

-Josh

On 2018-04-28 13:10:07-06:00 owner-namd-l_at_ks.uiuc.edu wrote:

I'm using namd 2.10
On some stage when I'm trying to restart from restart files, I'm getting a negative value of step and simulation stops.
I tried to modify parameters in my config file, but nothing helps.
any idea what may cause that?
Info: Startup phase 11 took 0.000886917 s, 367.414 MB of memory in use
Info: Startup phase 12 took 0.000576019 s, 367.414 MB of memory in use
Info: Finished startup at 1.9923 s, 367.414 MB of memory in use
TCL: Running for 200000000 steps
PRESSURE: 1950420000 2402.47 -42.0319 -320.275 -42.0319 2421.71 -277.166 -320.275 -277.166 2407.94
GPRESSURE: 1950420000 32.6546 191.427 -119.264 4.3597 -21.071 -303.503 -216.287 -254.52 -93.6979
ENERGY: 1950420000 12588.4484 9400.9788 2760.1154 157.2864 -161961.1152 14158.7388 0.0000 0.0000 36164.2852 -86731.2623 304.6062 -122895.5475 -86208.4985 304.6062 2410.7054 -27.3714 384618.8605 2410.7054 -27.3714
OPENING EXTENDED SYSTEM TRAJECTORY FILE
WRITING EXTENDED SYSTEM TO OUTPUT FILE AT STEP -2144547296
CLOSING EXTENDED SYSTEM TRAJECTORY FILE
WRITING COORDINATES TO OUTPUT FILE AT STEP -2144547296
COORDINATE DCD FILE namd_npt_20180428T155042.dcd WAS NOT CREATED

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