[gmx-users] g_energy_d average

[Justin Lemkul]

On 9/12/14 2:25 PM, Johnny Lu wrote:
> Hi.
>
> g_energy_d:
> Statistics over 901701 steps [ 0.0000 through 450.8500 ps ], 1 data sets
> All statistics are over 90171 points
>
> Energy                      Average   Err.Est.       RMSD  Tot-Drift
> -------------------------------------------------------------------------------
> Pressure                  0.0989539       0.96    151.279    1.08511  (bar)
>
> (g_energy gives same numbers)
>
> I use libreoffice spreadsheet to open the xvg file output by g_energy_d
>
> Spreadsheet average is 0.4817, over 9018 rows, with standard deviation 153.
>
> Why these two averages are different?
>

The .edr file stores energy history, so its statistics are accurate over all MD 
steps.  Post-processing of data stored only every nstenergy steps is limited to 
only those values.  The only way the two quantities agree is if nstenergy = 1.

-Justin

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

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

Department of Pharmaceutical Sciences
School of Pharmacy
Health Sciences Facility II, Room 601
University of Maryland, Baltimore
20 Penn St.
Baltimore, MD 21201

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

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