[gmx-users] Re: -dt option in g_velacc

[Mark Abraham]

On 12/08/2011 12:30 AM, Jinan Niu wrote:
> On 8/08/2011 11:08 PM, Mark Abraham wrote:
>
> >I don't quite follow your question, but for correlation functions to be
> >computed accurately, you need data collected much more frequently >than
> >the relevant time scales. That can require good planning.
> >Mark
> Hi,Mark and other gmx users:
> when I used g_velacc to calculate VAF,  I found the range of frequency 
> of the power spectrum is related with dt, so if is there is some 
> solutions? can the complication of gmx by double decision solve it?

If the value for g_velacc -dt is comparable to the correlation time 
scale of the system, then the results of an analysis will be sensitive 
to that value. In such cases, you need to use the smallest possible -dt 
value (i.e. omit the value) and/or collect data more frequently.

Mark
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