Hi,
The absolute value of the energies you get for a system don't really
tell you much, since the zero point is not well-defined. What is more
important is the relative energy between different conformations. So
in your case, the real question is "Is my final energy lower than my
initial energy?". If the answer is "yes", then the minimization ran
just fine (although whether you have run enough minimization is a
different question). If the answer is "no" then you may have a
problem...
-Dan
On Wed, Aug 3, 2016 at 7:43 AM, Stregone <stregone.protonmail.com> wrote:
> Good morning Amber users!!
>
> I am running a minimisation of a org. solvent box (bromobenzene),
> the box is 40x40x40, a small one.
> After the minimisation and the equilibrium, the energies (ETOT, EPTOT and EKTOT ),
> are positive, which should not be possible. I do not think that the problem is on the minimisation,
> so I assume that it should be on the NPT script.
>
> This is the script for the minimisation
> -----------------------------------------------------------------------------------------------------------------------
> minimisation
> &cntrl
> imin = 1, maxcyc = 80000, ntmin = 1,
> ntx = 1,
> ncyc = 25000,
> ntb = 1, ntp = 0,
> cut = 12.0
> /
> ----------------
> The last part of the output is something like this
> --------------->>>>
> NSTEP ENERGY RMS GMAX NAME NUMBER
> 80000 1.9963E+04 9.5323E-03 4.1860E-01 H7 20803
>
> BOND = 142.2302 ANGLE = 47287.8987 DIHED = 229.8498
> VDWAALS = -20567.1982 EEL = -6658.3096 HBOND = 0.0000
> 1-4 VDW = 1659.8453 1-4 EEL = -2131.1922 RESTRAINT = 0.0000
> --------------------------------------------------------------------------------
> 5. TIMINGS
> --------------------------------------------------------------------------------
> | Build the list 5.06 ( 8.70% of List )
> | Other 53.09 (91.30% of List )
> | List time 58.15 ( 1.55% of Nonbo)
> | Short_ene time 1839.59 (91.87% of Direc)
> | Other 162.84 ( 8.13% of Direc)
> | Direct Ewald time 2002.44 (54.17% of Ewald)
> | Adjust Ewald time 26.17 ( 0.71% of Ewald)
> | Self Ewald time 0.25 ( 0.01% of Ewald)
> | Fill Bspline coeffs 49.43 ( 8.46% of Recip)
> | Fill charge grid 39.85 ( 6.82% of Recip)
> | Scalar sum 79.28 (13.57% of Recip)
> | Grad sum 55.30 ( 9.46% of Recip)
> | FFT back comm time 67.48 (21.75% of FFT t)
> | Other 242.84 (78.25% of FFT t)
> | FFT time 310.32 (53.11% of Recip)
> | Other 50.16 ( 8.58% of Recip)
> | Recip Ewald time 584.34 (15.81% of Ewald)
> | Force Adjust 1022.74 (27.66% of Ewald)
> | Virial junk 42.43 ( 1.15% of Ewald)
> | Start synchronizatio 0.32 ( 0.01% of Ewald)
> | Other 18.21 ( 0.49% of Ewald)
> | Ewald time 3696.90 (98.45% of Nonbo)
> | Nonbond force 3755.26 (89.55% of Force)
> | Bond/Angle/Dihedral 82.15 ( 1.96% of Force)
> | FRC Collect time 201.65 ( 4.81% of Force)
> | Other 154.20 ( 3.68% of Force)
> | Force time 4193.25 (100.0% of Runmd)
> | Runmd Time 4193.25 (93.41% of Total)
> | Other 295.86 ( 6.59% of Total)
> | Total time 4489.15 (100.0% of ALL )
> -----------------------------------------------------------------------------------------------------------------------
> The NPT is the following :
>>>NPT - Bromobenzene
>>>&cntrl
>>>imin = 0,
>>>irest = 0, ntx = 1, ntc = 2,
>>>ntb = 2, cut = 13.0,
> ntp = 1, taup = 1.0, pres0 = 1.013,
> tempi = 298.15, temp0 = 298.15,
> ntt = 3, gamma_ln = 3.0, ig = -1,
> nstlim = 600000, dt = 0.0005,
> ntpr = 200, ntwx = 200, ntwr = 200, ntwe = 200,
> /
> &ewald
> skinnb = 2.0
> /
> -----------------------------------------------------------------------------------------------------------------------------
> I read big part of the manual, -Sander- so most of the commands come from there and
> the suggestions into it.
> I started a new simulation few minutes ago, so I am attaching the NPT so far !!
> As you can see, the energies are positive.
>
> I would appreciate any advise. Thanks before hand.
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>
--
-------------------------
Daniel R. Roe, PhD
Department of Medicinal Chemistry
University of Utah
30 South 2000 East, Room 307
Salt Lake City, UT 84112-5820
http://home.chpc.utah.edu/~cheatham/
(801) 587-9652
(801) 585-6208 (Fax)
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Received on Wed Aug 03 2016 - 13:00:02 PDT
