[gmx-users] -dt

[Tsjerk Wassenaar]

Hi,

In the mathematical sense, gromacs will only use the frames in the
trajectory for which time modulus dt equals 0 (time % dt == 0).

Cheers,

Tsjerk

On Wed, Jun 30, 2010 at 11:47 AM, XAvier Periole <x.periole at rug.nl> wrote:
> -dt will define the frequency of analysis that a program will do.
>
> In the cases you mention (time step = 4 fs) the program is using the frames according to -dt you give and their availability in the trajectory.
>
> On Jun 30, 2010, at 11:01, leila karami <karami.leila1 at gmail.com> wrote:
>
>> Hi gromacs users
>>
>> I want to know what is purpose of -dt flag in most of commands? in my analysis, different values for -dt
>> results in outcomes have not determined trend .
>>
>> I used this flag for g_rms as follows :
>>
>> if   g_rms -f pr.xtc -s pr.tpr -n pr.ndx    -o 5.xvg  -dt 5   so :
>>
>> gromacs record output every 20 ps
>>
>> if   g_rms -f pr.xtc -s pr.tpr -n pr.ndx    -o 10.xvg  -dt 10  so :
>>
>> gromacs record output every 20 ps
>>
>> if   g_rms -f pr.xtc -s pr.tpr -n pr.ndx    -o 15.xvg  -dt 15  so :
>>
>> gromacs record output every 60 ps
>>
>> if   g_rms -f pr.xtc -s pr.tpr -n pr.ndx    -o 20.xvg  -dt 20  so :
>>
>> gromacs record output every 20 ps
>>
>> if   g_rms -f pr.xtc -s pr.tpr -n pr.ndx    -o 25.xvg  -dt 25  so :
>>
>> gromacs record output every 100 ps
>>
>> if   g_rms -f pr.xtc -s pr.tpr -n pr.ndx    -o 30.xvg  -dt 30    so :
>>
>> gromacs record output every 60 ps
>>
>>
>> in my simulation [ 1 frame = 4 ps ]
>>
>> any help will highly appreciated.
>>
>>
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-- 
Tsjerk A. Wassenaar, Ph.D.

post-doctoral researcher
Molecular Dynamics Group
Groningen Institute for Biomolecular Research and Biotechnology
University of Groningen
The Netherlands