Dear Christoph,

Thank you for the clarifications.

I have another question. I was just verifying by hand the bonded potential 
which we get by using the Simple Boltzmann Inversion method. Say for 
example for a Dihedral distribution. The first few data points from 
dist.tgt file is shown below:

-3.14159     0.456519
-3.07876     0.897376
-3.01593     0.866437
-2.95309     0.825311
-2.89026     0.760535

Now, for the first data point if I try to get the potential by hand by 
using the formula *U(q) = -**kBT** ln **P(q), *I am getting the value 
*1.95587*. But the value which VOTCA gives me is *1.72411.*
Can you please explain the reason for this discrepancy?

Here are the first few data points from the potential table:

-3.14159        1.72411                     40.8857
-3.09942        0                                  20.0311
-3.05725        0.0347262                 -1.32404
-3.01508        0.111667                   -1.92226
-2.97291        0.196846                    -2.01054

Thank you.

Sanjeet

On Wednesday, October 19, 2022 at 7:02:32 PM UTC-4 Christoph Junghans wrote:

> On Wed, Oct 19, 2022 at 13:00 Sanjeet Singh <[email protected]> wrote:
>
>> Hello Christoph,
>>
>> Sorry for the incessant questioning.
>>
>> I got the point that csg_inverse will do the extension automatically. But 
>> when I am using Boltzmann Inversion (not IBI) to get the bonded potential, 
>> then do I need to do the modifications (extending the range of the 
>> potential) manually by using the post-processing tools in VOTCA? Or can I 
>> use csg_inverse for simple Boltzmann Inversion also? 
>>
> yes, when you do BI then you need to do it manually! Of course you can do 
> IBI for just one step and steal the potential from there ;-)
>
> Christoph
>
>
>> Thank you.
>>
>> Sanjeet
>>
>>  
>>
>> On Wednesday, October 19, 2022 at 12:17:04 PM UTC-4 Christoph Junghans 
>> wrote:
>>
>>> On Wed, Oct 19, 2022 at 9:24 AM Sanjeet Singh <[email protected]> 
>>> wrote: 
>>> > 
>>> > Dear Christoph, 
>>> > 
>>> > I would like to ask a follow-up question to this. Now, suppose I set 
>>> my min = 0.351 and max = 0.367, then I will be getting my potential in this 
>>> range. What if I want to extend my potential outside this range, Say for 
>>> example the range of my dist.tgt file. The range of my dist.tgt file is 
>>> 0.347465 to 0.371461. It's just that in the boundary regions of dist.tgt 
>>> file I don't have a proper sampling. 
>>>
>>> csg_inverse would to the extension automatically, for manually 
>>> modification see: 
>>>
>>> https://www.votca.org/csg/preparing.html?highlight=extrapolate#post-processing-of-the-potential
>>>  
>>>
>>> Christoph 
>>> > 
>>> > On Wednesday, October 19, 2022 at 9:05:53 AM UTC-4 Christoph Junghans 
>>> wrote: 
>>> >> 
>>> >> On Tue, Oct 18, 2022 at 6:30 PM Sanjeet Singh <[email protected]> 
>>> wrote: 
>>> >> > 
>>> >> > Hello Christoph, 
>>> >> > 
>>> >> > Thank you for your prompt response. But, I am not able to follow 
>>> you when you say "for csg_botlzmann it doesn't really matter". 
>>> >> What I meant there was that csg_boltzmann will invert things either 
>>> >> way, but what I would do is to pick min and max inside the peak of 
>>> the 
>>> >> distribution, so 0.351 and 0.367, as you suggested, should work. 
>>> >> 
>>> >> Christoph 
>>> >> 
>>> >> > 
>>> >> > For example in my dist.tgt file here, I have initial data points as 
>>> follows: 
>>> >> > 
>>> >> > 0.347465 0.00833478 
>>> >> > 0.347705 0.00833478 
>>> >> > 0.347945 0.0166696 
>>> >> > 0.348185 0 
>>> >> > 0.348425 0.00833478 
>>> >> > 
>>> >> > Therefore, when I am using this dist.tgt file to get bonded 
>>> potential using Boltzmann Inversion I am setting the min at 0.348425 as 
>>> before this I am having a point with zero probability. 
>>> >> > 
>>> >> > Or if I set my min at the starting point 0.347465, then will this 
>>> be OK? 
>>> >> > 
>>> >> > 
>>> >> > On Tuesday, October 18, 2022 at 6:30:42 PM UTC-4 Christoph Junghans 
>>> wrote: 
>>> >> >> 
>>> >> >> On Tue, Oct 18, 2022 at 12:43 PM Sanjeet Singh <[email protected]> 
>>> wrote: 
>>> >> >> > 
>>> >> >> > Hello Christoph, 
>>> >> >> > 
>>> >> >> > I have run a 1000 ns atomistic vacuum simulation to get bonded 
>>> distribution with exclusions obtained using the following command: 
>>> >> >> > 
>>> >> >> > csg_boltzmann --top topology.xml --cg mapping.xml --excl 
>>> exclusions.txt 
>>> >> >> > 
>>> >> >> > Then, I am getting my bonded distribution using the following 
>>> command: 
>>> >> >> > 
>>> >> >> > csg_boltzmann --top topology.xml --trj Trajectory2.dump --cg 
>>> PEO-10.xml --first-frame 500000 < boltzmann_cmds_dist 
>>> >> >> > 
>>> >> >> > After getting my bonded distribution I want to use Boltzmann 
>>> Inversion to get my bonded potential using the following command: 
>>> >> >> > 
>>> >> >> > csg_boltzmann --top topology.xml --trj Trajectory2.dump --cg 
>>> PEO-10.xml --first-frame 500000 < boltzmann_cmds 
>>> >> >> > 
>>> >> >> > Now, suppose I want to do the Boltzmann Inversion for a Bond-AB 
>>> for which I am using the boltzmann_cmds file with the following options: 
>>> >> >> > 
>>> >> >> > tab set T 300 
>>> >> >> > tab set scale bond #SCALING IS NEEDED TO GET THE VOLUME 
>>> NORMALIZED DISTRIBUTION FUNCTION i.e. dividing the distribution by 4pir^2 
>>> >> >> > tab set auto 0 
>>> >> >> > tab set min ______ 
>>> >> >> > tab set max _____ 
>>> >> >> > tab set n 100 
>>> >> >> > tab bond-AB.potential-file-100.ib *bond-AB* 
>>> >> >> > 
>>> >> >> > Then in the above lines, what should be the value of min and 
>>> max? 
>>> >> >> > 
>>> >> >> > I am attaching the bonded distribution file for BOND-AB here, 
>>> and also the plot of BOND-AB distribution. 
>>> >> >> > 
>>> >> >> > If I go by the BOND-AB distribution file, then maybe I can use 
>>> min = 0.348425, and max = 0.369061. As before this min and after the max 
>>> value, I have 0 probability for some bond length. 
>>> >> >> > 
>>> >> >> > Or, should I select min and max from the plot of the 
>>> distribution? And select min = 0.351, and max = 0.367, i.e. the range where 
>>> I have the normal distribution in the plot. 
>>> >> >> Short answer is for csg_botlzmann it doesn't really matter. 
>>> >> >> However, for csg_inverse the min and max matter, so the boltzmann 
>>> >> >> inversion from the target distribution (<name>.dist.tgt) is done 
>>> >> >> correctly, if you don't provide an initial guess for the potential 
>>> >> >> (<name>.pot.in) 
>>> >> >> 
>>> >> >> Christoph 
>>> >> >> 
>>> >> >> > 
>>> >> >> > Thank you. I would appreciate any advice you have for me. 
>>> >> >> > 
>>> >> >> > 
>>> >> >> > -- 
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>>>  
>>>
>>> >> >> 
>>> >> >> 
>>> >> >> 
>>> >> >> -- 
>>> >> >> Christoph Junghans 
>>> >> >> Web: http://www.compphys.de 
>>> >> > 
>>> >> > -- 
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>>>  
>>>
>>> >> 
>>> >> 
>>> >> 
>>> >> -- 
>>> >> Christoph Junghans 
>>> >> Web: http://www.compphys.de 
>>> > 
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>>>  
>>>
>>>
>>>
>>>
>>> -- 
>>> Christoph Junghans 
>>> Web: http://www.compphys.de 
>>>
>> -- 
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>> .
>>
> -- 
> Christoph Junghans
> Web: http://www.compphys.de
>

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