Regarding Trajectory files for force matching

[Sanjeet Singh]

Hello Everyone,

I am new to force matching. I want to use force matching for LAMMPS dump file. 

I would like to know that do I need to have separate trajectory file containing force data on each atom, or a single file containing both the coordinates and trajectory information is sufficient for force matching.

Sorry for my ignorance on the matter.

Thank you,

Sanjeet

[Christoph Junghans]

On Wed, Feb 1, 2023, 18:48 Sanjeet Singh <sanje...@gmail.com> wrote:

Hello Everyone,

I am new to force matching. I want to use force matching for LAMMPS dump file. 

I would like to know that do I need to have separate trajectory file containing force data on each atom, or a single file containing both the coordinates and trajectory information is sufficient for force matching.

You need a single trajectory file.

Sorry for my ignorance on the matter.

Thank you,

Sanjeet

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[Sanjeet Singh]

Dear Christoph,

Thank you for your reply.

I have another question about min and max from force matching tutorial of hexane.

  <non-bonded>
    <name>A-A</name>
    <type1>A</type1>
    <type2>A</type2>
    <min>0</min>
    <max>2.5</max>
    <step>0.01</step>

What is the use of min & max in the above code?

<fmatch>
      <min>0.34</min>
      <max>1.0</max>
      <step>0.02</step>
      <out_step>0.01</out_step>
    </fmatch>

As far as I understand the min and max in the above code are used for force matching. And the values of this min and max we get from the distribution file of the respective interactions such that we have appreciable probabilities in this range.

Also, what is the use of the following command:

csg_call table linearop bond.pot bond.pot -1 0

Is it simply to multiply the obtained potential by -1, as force is the -ve derivative of potential?

Thank you.

Sanjeet

[Christoph Junghans]

On Fri, Feb 3, 2023 at 12:47 PM Sanjeet Singh <sanje...@gmail.com> wrote:
>
> Dear Christoph,
>
> Thank you for your reply.
>
> I have another question about min and max from force matching tutorial of hexane.
>
> <non-bonded>
> <name>A-A</name>
> <type1>A</type1>
> <type2>A</type2>
> <min>0</min>
> <max>2.5</max>
> <step>0.01</step>
>
> What is the use of min & max in the above code?

This min/max/step are not used in force matching, we just left them
there, so you could use the same file for csg_stat to calculate
distributions.

>
> <fmatch>
> <min>0.34</min>
> <max>1.0</max>
> <step>0.02</step>
> <out_step>0.01</out_step>
> </fmatch>
>
> As far as I understand the min and max in the above code are used for force matching. And the values of this min and max we get from the distribution file of the respective interactions such that we have appreciable probabilities in this range.

Correct!

>
> Also, what is the use of the following command:
>
> csg_call table linearop bond.pot bond.pot -1 0
>
> Is it simply to multiply the obtained potential by -1, as force is the -ve derivative of potential?

Correct.

>
> Thank you.
>
> Sanjeet
>
>
>
> On Thursday, February 2, 2023 at 8:41:58 AM UTC-5 Christoph Junghans wrote:
>>
>>
>>
>> On Wed, Feb 1, 2023, 18:48 Sanjeet Singh <sanje...@gmail.com> wrote:
>>>
>>> Hello Everyone,
>>>
>>> I am new to force matching. I want to use force matching for LAMMPS dump file.
>>>
>>> I would like to know that do I need to have separate trajectory file containing force data on each atom, or a single file containing both the coordinates and trajectory information is sufficient for force matching.
>>
>> You need a single trajectory file.
>>
>>>
>>> Sorry for my ignorance on the matter.
>>>
>>> Thank you,
>>>
>>> Sanjeet
>>>
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>
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