There will almost always be *some* drift due to small roundoff errors. It
may also be useful to look at drift in terms of temperature. If necessary,
you can reduce the drift by changing some tolerances, such as tightening
dsum_tol and tol parameters by an order of magnitude (to 1e-6).
James
On Sun, Oct 12, 2014 at 10:43 PM, zhangmk <zhangmk69.gmail.com> wrote:
> Dear professors:
>
> Recently, I simulated polypeptides in aqueous solution in a 6.8 nm square
> system. First, following the tutorial presentations, I do min, heat,
> density, equil process.Then the system were calculated in NVT ensemble for
> 5 ns to reach balance, the script like this:
>
> Vol Ala30HX2Sol
>
> &cntrl
>
> imin=0,irest=1,ntx=5,
>
> nstlim=5000000,dt=0.001,
>
> ntc=2,ntf=2,
>
> cut=10.0, ntb=1,
>
> ntpr=20000, ntwx=20000,ntwr=-100000,
>
> ntt=3, gamma_ln=3.0, temp0=310.0,
>
> /
>
> Finally, a 5ns NVE simulation was conducted, the script follows:
>
> Ene Ala30HX2Sol
>
> &cntrl
>
> imin=0, irest=1, ntx=5,
>
> nstlim=5000000, dt=0.001,
>
> ntb=1, ntt=0,
>
> cut=10.0,
>
> ntc=2, ntf=2,
>
> ntpr=20000, ntwx=20000,ntwr=-100000,
>
> /
>
> But in the NVE simulation, I find that the total energy of the system is
> on the rise In the attached file, how this thing happened? should be the
> ETOT unchanged in NVE?
>
>
> --
> ---------------------------------------------------------------------
> ZhangMK
> +8623-63063582
> Chongqing Institute of Green and Intelligent Technology of Chinese Academy
> Sciences.
>
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Received on Sun Oct 12 2014 - 20:00:03 PDT
