[gmx-users] Regarding DispCorr

[Mark Abraham]

On 20/02/2012 4:19 PM, bipin singh wrote:
> Thanks for your help. But I am getting different results for potential
> energy when minimization done applying DispCorr=EnerPres and
> minimization done without DispCorr. Please provide your suggestions

They will be different, but they are highly unlikely to be 
*significantly* different. Slight changes in the nearly symmetric effect 
of long-range interactions are not going to change the general nature of 
the local minimum that you approach with EM - and decidedly not if all 
you are doing is preparing to do dynamics. Doing those dynamics is a 
different matter.

Mark

>
> My mdp for minimization is as follows:
>
> define= -DFLEXIBLE
> constraints =  none
> integrator= steep
> dt= 0.002; ps !
> nsteps= 500000
> nstlist= 1
> ns_type= grid
> rlist= 1.0
> coulombtype= PME
> vdwtype= cut-off
> rcoulomb= 1.0
> rvdw= 1.0
> DispCorr=EnerPres ; (and No DispCorr for other case)
> fourierspacing= 0.12
> fourier_nx= 0
> fourier_ny= 0
> fourier_nz= 0
> pme_order= 4
> ewald_rtol= 1e-5
> optimize_fft= yes
> emtol=100.0
> emstep=0.01
> pbc=xyz
>
>
> On Mon, Feb 20, 2012 at 05:03, Mark Abraham<Mark.Abraham at anu.edu.au>  wrote:
>> On 20/02/2012 2:23 AM, bipin singh wrote:
>>> Hello,
>>> Thanks for reply.
>>> As given in the manual, If we give DispCorr=EnerPres it will apply
>>> long range dispersion corrections for Energy and Pressure.
>>> But I don't know whether it is logical to apply this during energy
>>> minimization.
>>
>> Manual 4.8 sets out some conditions for its use. It is likely from the
>> nature of EM that it doesn't matter either way.
>>
>> Mark
>>
>>
>>> On Sun, Feb 19, 2012 at 20:20, Mark Abraham<Mark.Abraham at anu.edu.au>
>>>   wrote:
>>>> On 19/02/2012 11:21 PM, bipin singh wrote:
>>>>> Hello,
>>>>>
>>>>> Please let me know, Whether it is correct to use DispCorr=EnerPres
>>>>> during energy minimization.
>>>>>
>>>> What does it do?
>>>>
>>>> Mark
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>
>