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

[Tsjerk Wassenaar]

For a single configuration of ethanol, you can do the calculations on a
piece of paper and see if you're doing better than Gromacs.

Cheers,

Tsjerk

On Thu, Oct 30, 2014 at 8:27 AM, David van der Spoel <spoel at xray.bmc.uu.se>
wrote:

> 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
> --
> Gromacs Users mailing list
>
> * Please search the archive at http://www.gromacs.org/
> Support/Mailing_Lists/GMX-Users_List before posting!
>
> * Can't post? Read http://www.gromacs.org/Support/Mailing_Lists
>
> * For (un)subscribe requests visit
> https://maillist.sys.kth.se/mailman/listinfo/gromacs.org_gmx-users or
> send a mail to gmx-users-request at gromacs.org.
>



-- 
Tsjerk A. Wassenaar, Ph.D.