Re: [gmx-users] autocorrelation function of hydrogen bond : g_hbond

2013-04-09 Thread Paulo Netz
No, this oscillation is related to libration.
See, for instance

http://www.princeton.edu/~fhs/rahman/rahman.pdf

esp. Fig. 24 in this paper

Best regards

Paulo Netz


On Tue, Apr 9, 2013 at 2:38 PM, Nilesh Dhumal wrote:

> Is oscillation is because of change in hydrogen bonded distance?
>
> Do program consider the change in hydrogen bonded distance during ACF
> calculation?
>
> Nilesh
>
> > There's a known oscillation in the ACF that occurs at ~100 fs or so. Is
> > that what you see?
> >
> > Erik
> >
> > On 9 Apr 2013, at 18:02, Nilesh Dhumal  wrote:
> >
> >>
> >>
> >>> On Tue, Apr 9, 2013 at 11:47 AM, Nilesh Dhumal
> >>> wrote:
> >>>
>  Hello,
> 
>  I am calculating the hydrogen bond autocorrelation function using
>  g_hbond
>  for O-H---O hydrogen bond in system.
> 
>  I made two groups 1. O-H atoms numbers 2. two oxygen atoms are
>  interacting
>  with OH bond.
> 
>  I am using default hydrogen bond criteria (donor-acceptor distance 3.5
>  and
>  angle 30) for calculating the autocorrelation function.
> 
>  I am not getting a smooth exponential plot. I get a small bump in the
>  plot.
> 
>  Attached the autocorrelation plot.
> 
> 
> >>> Attachments are not allowed on this list. Please provide a link to the
> >>> image.
> >>>
> >>>
>  Why there is not smooth exponential plot.
> 
> >>>
> >>> There is no way to tell, and even with the image there is still no way
> >>> to
> >>> tell. How much sampling do you have? Have you looked at overall
> >>> convergence, etc?
> >>
> >>
> >> I saved the trajectory at 3fs.
> >>
> >> It converged.
> >>
> >> Nilesh
> >>
> >>
> >>
> >>
> >>>
> >>> -Justin
> >>>
> >>> --
> >>>
> >>> 
> >>>
> >>> Justin A. Lemkul, Ph.D.
> >>> Research Scientist
> >>> Department of Biochemistry
> >>> Virginia Tech
> >>> Blacksburg, VA
> >>> jalemkul[at]vt.edu | (540)
> >>> 231-9080http://www.bevanlab.biochem.vt.edu/Pages/Personal/justin
> >>>
> >>> 
> >>> --
> >>> gmx-users mailing listgmx-users@gromacs.org
> >>> http://lists.gromacs.org/mailman/listinfo/gmx-users
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> >>>
> >>
> >>
> >> --
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Re: [gmx-users] autocorrelation function of hydrogen bond : g_hbond

2013-04-09 Thread Nilesh Dhumal
Is oscillation is because of change in hydrogen bonded distance?

Do program consider the change in hydrogen bonded distance during ACF
calculation?

Nilesh

> There's a known oscillation in the ACF that occurs at ~100 fs or so. Is
> that what you see?
>
> Erik
>
> On 9 Apr 2013, at 18:02, Nilesh Dhumal  wrote:
>
>>
>>
>>> On Tue, Apr 9, 2013 at 11:47 AM, Nilesh Dhumal
>>> wrote:
>>>
 Hello,

 I am calculating the hydrogen bond autocorrelation function using
 g_hbond
 for O-H---O hydrogen bond in system.

 I made two groups 1. O-H atoms numbers 2. two oxygen atoms are
 interacting
 with OH bond.

 I am using default hydrogen bond criteria (donor-acceptor distance 3.5
 and
 angle 30) for calculating the autocorrelation function.

 I am not getting a smooth exponential plot. I get a small bump in the
 plot.

 Attached the autocorrelation plot.


>>> Attachments are not allowed on this list. Please provide a link to the
>>> image.
>>>
>>>
 Why there is not smooth exponential plot.

>>>
>>> There is no way to tell, and even with the image there is still no way
>>> to
>>> tell. How much sampling do you have? Have you looked at overall
>>> convergence, etc?
>>
>>
>> I saved the trajectory at 3fs.
>>
>> It converged.
>>
>> Nilesh
>>
>>
>>
>>
>>>
>>> -Justin
>>>
>>> --
>>>
>>> 
>>>
>>> Justin A. Lemkul, Ph.D.
>>> Research Scientist
>>> Department of Biochemistry
>>> Virginia Tech
>>> Blacksburg, VA
>>> jalemkul[at]vt.edu | (540)
>>> 231-9080http://www.bevanlab.biochem.vt.edu/Pages/Personal/justin
>>>
>>> 
>>> --
>>> gmx-users mailing listgmx-users@gromacs.org
>>> http://lists.gromacs.org/mailman/listinfo/gmx-users
>>> * Please search the archive at
>>> http://www.gromacs.org/Support/Mailing_Lists/Search before posting!
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>>> www interface or send it to gmx-users-requ...@gromacs.org.
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>>>
>>
>>
>> --
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>
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Re: [gmx-users] autocorrelation function of hydrogen bond : g_hbond

2013-04-09 Thread Erik Marklund
There's a known oscillation in the ACF that occurs at ~100 fs or so. Is that 
what you see?

Erik

On 9 Apr 2013, at 18:02, Nilesh Dhumal  wrote:

> 
> 
>> On Tue, Apr 9, 2013 at 11:47 AM, Nilesh Dhumal
>> wrote:
>> 
>>> Hello,
>>> 
>>> I am calculating the hydrogen bond autocorrelation function using
>>> g_hbond
>>> for O-H---O hydrogen bond in system.
>>> 
>>> I made two groups 1. O-H atoms numbers 2. two oxygen atoms are
>>> interacting
>>> with OH bond.
>>> 
>>> I am using default hydrogen bond criteria (donor-acceptor distance 3.5
>>> and
>>> angle 30) for calculating the autocorrelation function.
>>> 
>>> I am not getting a smooth exponential plot. I get a small bump in the
>>> plot.
>>> 
>>> Attached the autocorrelation plot.
>>> 
>>> 
>> Attachments are not allowed on this list. Please provide a link to the
>> image.
>> 
>> 
>>> Why there is not smooth exponential plot.
>>> 
>> 
>> There is no way to tell, and even with the image there is still no way to
>> tell. How much sampling do you have? Have you looked at overall
>> convergence, etc?
> 
> 
> I saved the trajectory at 3fs.
> 
> It converged.
> 
> Nilesh
> 
> 
> 
> 
>> 
>> -Justin
>> 
>> --
>> 
>> 
>> 
>> Justin A. Lemkul, Ph.D.
>> Research Scientist
>> Department of Biochemistry
>> Virginia Tech
>> Blacksburg, VA
>> jalemkul[at]vt.edu | (540)
>> 231-9080http://www.bevanlab.biochem.vt.edu/Pages/Personal/justin
>> 
>> 
>> --
>> gmx-users mailing listgmx-users@gromacs.org
>> http://lists.gromacs.org/mailman/listinfo/gmx-users
>> * Please search the archive at
>> http://www.gromacs.org/Support/Mailing_Lists/Search before posting!
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>> 
> 
> 
> -- 
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Re: [gmx-users] autocorrelation function of hydrogen bond : g_hbond

2013-04-09 Thread Nilesh Dhumal


> On Tue, Apr 9, 2013 at 11:47 AM, Nilesh Dhumal
> wrote:
>
>> Hello,
>>
>> I am calculating the hydrogen bond autocorrelation function using
>> g_hbond
>> for O-H---O hydrogen bond in system.
>>
>> I made two groups 1. O-H atoms numbers 2. two oxygen atoms are
>> interacting
>> with OH bond.
>>
>> I am using default hydrogen bond criteria (donor-acceptor distance 3.5
>> and
>> angle 30) for calculating the autocorrelation function.
>>
>> I am not getting a smooth exponential plot. I get a small bump in the
>> plot.
>>
>> Attached the autocorrelation plot.
>>
>>
> Attachments are not allowed on this list. Please provide a link to the
> image.
>
>
>> Why there is not smooth exponential plot.
>>
>
> There is no way to tell, and even with the image there is still no way to
> tell. How much sampling do you have? Have you looked at overall
> convergence, etc?


I saved the trajectory at 3fs.

It converged.

Nilesh




>
> -Justin
>
> --
>
> 
>
> Justin A. Lemkul, Ph.D.
> Research Scientist
> Department of Biochemistry
> Virginia Tech
> Blacksburg, VA
> jalemkul[at]vt.edu | (540)
> 231-9080http://www.bevanlab.biochem.vt.edu/Pages/Personal/justin
>
> 
> --
> gmx-users mailing listgmx-users@gromacs.org
> http://lists.gromacs.org/mailman/listinfo/gmx-users
> * Please search the archive at
> http://www.gromacs.org/Support/Mailing_Lists/Search before posting!
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>


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Re: [gmx-users] autocorrelation function of hydrogen bond : g_hbond

2013-04-09 Thread Justin Lemkul
On Tue, Apr 9, 2013 at 11:47 AM, Nilesh Dhumal wrote:

> Hello,
>
> I am calculating the hydrogen bond autocorrelation function using g_hbond
> for O-H---O hydrogen bond in system.
>
> I made two groups 1. O-H atoms numbers 2. two oxygen atoms are interacting
> with OH bond.
>
> I am using default hydrogen bond criteria (donor-acceptor distance 3.5 and
> angle 30) for calculating the autocorrelation function.
>
> I am not getting a smooth exponential plot. I get a small bump in the plot.
>
> Attached the autocorrelation plot.
>
>
Attachments are not allowed on this list. Please provide a link to the
image.


> Why there is not smooth exponential plot.
>

There is no way to tell, and even with the image there is still no way to
tell. How much sampling do you have? Have you looked at overall
convergence, etc?

-Justin

-- 



Justin A. Lemkul, Ph.D.
Research Scientist
Department of Biochemistry
Virginia Tech
Blacksburg, VA
jalemkul[at]vt.edu | (540)
231-9080http://www.bevanlab.biochem.vt.edu/Pages/Personal/justin


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