[gmx-users] why the gas ethanol system has positive potential?

[David van der Spoel]

On 2014-10-30 07:27, weiduo zhu wrote:
> Dear sir,
>
>       I’m trying to simulate a ethanol gas system, only one ethanol
> molecule in 10*10*10nm box. but when I analysis the energy, it shows
> that potential is positive, and the Coul.recip term is very positive
> throughout the entire run. I think the long range electrostatics
> (calculated with cutoff) is not okay. But when I simulate liquid
> ethanol, the potential is okay. I don’t know why this would happen. I
> need your help, thank you!
>
> nstlist  = 0
>
> ns_type = simple
>
> pbc     = no
>
> rlist     = 0
>
> coulombtype        = cutoff
>
> rcoulomb-switch     = 0
>
> rcoulomb           = 0
>
> vdw-type           = cutoff
>
> rvdw-switch         = 0
>
> rvdw               = 0
>
>                                                                  from:
>   Weiduo Zhu
>
Please post this kind of questions on the mailing list. A positive 
potential is normal, the only thing that matters is the difference in 
energy between gas phase and condensed phase.

-- 
David van der Spoel, Ph.D., Professor of Biology
Dept. of Cell & Molec. Biol., Uppsala University.
Box 596, 75124 Uppsala, Sweden. Phone:	+46184714205.
spoel at xray.bmc.uu.se    http://folding.bmc.uu.se