[gmx-users] g_dipole: dipole moment autocorrelation function

[David van der Spoel]

On 2011-03-30 20.16, Nilesh Dhumal wrote:
> Thanks.
> How can I take average.
summing up and dividing by the number of sims.
>
> How much long I should run the simulation.
until the average converges.
>
> Nilesh
>
> On Wed, March 30, 2011 12:59 pm, David van der Spoel wrote:
>> On 2011-03-30 18.54, Nilesh Dhumal wrote:
>>
>>> Hello,
>>>
>>>
>>> I am trying to calculate the dipole moment autocorrelation
>>> function for my system (ionic liquid). I am using gromacs 4.0.7 version.
>>>
>>>
>>> I run the simulation for 4 ns.  I run the following command to
>>> calculate the dipole moment autocorrelation function
>>>
>>> g_dipoles -f water.trr -s water.tpr -corr total -c
>>>
>>> The function is not geting converge to zero.
>>>
>>>
>>> I want to use this data for calculation of power spectra by fourier
>>> transfom of dipole moment autocorrelation function.
>>>
>>> Can you tell why its not geting converge to zero?
>>>
>>>
>> You have to simulate at least a few 10s of ns for such slow liquids to
>> converge. Alternatively you can average over many independent simulations
>> (10s).
>>
>>>
>>> Thanks
>>>
>>>
>>> Nilesh
>>>
>>>
>>>
>>>
>>
>>
>> --
>> 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 --
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>
>


-- 
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