[gmx-users] Re: long range energy

Alan Dodd anoddlad at yahoo.com
Mon Jan 22 15:33:17 CET 2007

Incidentally, if PME has been specified correctly, am I right in assuming there should be an energy term available within g_energy for long range forces?  Which one is it?  For some reason, I haven't been able to find it yet.

----- Original Message ----
From: Richard Vadnais <Richard.Vadnais at usherbrooke.ca>
To: gmx-users at gromacs.org
Sent: Monday, January 22, 2007 1:46:52 PM
Subject: [gmx-users] Re: long range energy

> Richard Vadnais wrote:
>> hi all,
>>     I want to find four types of energies from my simulation:  LJ and
>> Coulomb at long and short range. I use PME for coulomb type and cut-off
>> for VdW type with rlist = rcoulomb = 0.9
>>    However, the LJ (LR) and Coulomb LR are not generated in the output
>> nor can I get them with g_energy.
> That's because they aren't defined when rlist = rcoulomb. Have a read of
> the relevant manual sections.
> Mark
   I read these sections and this is where I am confused. It is specified 
that PME cannot be used with rlilst different than rcoulomb but that if they 
are egal, long range energies would not be defined. However, I am trying to 
reproduce a simulation done by a former member of our research group and 
from the input files (.mdp) he used, I found that he used:

rlist = 1.05
rcoulomb 1.15
coulombtype = PME

    From what I gathered from the manual, this combinaison is not possible, 
however, not only did he get results from this input, but he had the four 
types of energies: LJ-(SR), LJ-(LR), coulomb-(SR), coulomb-(LR).
   (I should have been more precise in my first post. I apologies.)

   thanks for your help,

Richard Vadnais,

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