Re: Force field design

From: Kenno Vanommeslaeghe (
Date: Wed Jul 23 2014 - 18:20:53 CDT

I think Axel is right; you really need to talk with your PI about spending
a few months in an MD lab. Universities and granting agencies commonly
have funds for a grad student to do so, so he has everything to win and
nothing to lose. And that goes double for you.

As for your complaint about perceived lack of online resources, to
continue with the analogy from my posts on the CHARMM forums (do read
them), if you buy an NMR or X-ray crystallography machine, the vendor will
provide you with manuals and training to allow you to use the machine at a
*technical* level. However, this alone will *not* allow you to use the
machine to solve scientific problems. For that, you also need:
- scientific background
- the know-how to combine you scientific background and technical skills
into effective research and valid/relevant results
Scientific background you can get from university courses and textbooks,
but there's no way to obtain know-how but to learn it form a more senior
researcher. No vendor in the world provides training for *that*. Also, you
don't seem to realize we are not vendors; we are academics. Our main
priority is to publish, and even though you may not experience it as such,
we're only helping the community out of kindness. But, we cannot help the
"many users like you", especially not over e-mail; that's like trying to
empty an ocean with a teaspoon (while it's raining). We're mainly here to
help the people who have gone through the effort of acquiring know-how
solve nontrivial problems that are poorly documented or not common
knowledge in the community.

On 07/23/2014 01:23 AM, Abhishek TYAGI wrote:
> Dear Axel,
> Thankyou for your elaborated email reply, I am agree few of the points but not all, their are many users like me using NAMD and try to learn it by online resources available, and I think most of them face these problems during their work that I am facing right now. I have to all the things myself I appreciate your way of explaining each and every point in detail, this will help me to plan my work in future.
> regards
> Abhishek
> ________________________________________
> From: Axel Kohlmeyer <>
> Sent: Wednesday, July 23, 2014 12:36 PM
> To: Abhishek TYAGI
> Cc:
> Subject: Re: namd-l: Force field design
> On Wed, Jul 23, 2014 at 12:04 AM, Abhishek TYAGI
> <> wrote:
>> Dear Axel,
>> Following points I need your views:
>> 1. First thing is that I am willing to learn NAMD and related MD skills for my research work, although my lab do not have subsequent knowledge about it, but still this one of the powerful tool for research work.
> so attend lectures, attend tutorials, invite people to come visit and
> teach you or go spend some time at a group that has the necessary
> expertise. if you are willing you have to be willing to learn things
> *the right way*. at the moment, you are *not* doing this. remember
> that with great power comes great responsibility.
>> 2. If you demotivate everyone like this than in future the NAMD user number will be effected.
> so what? this is not a competition about how many users a software
> has. that is a stupid way of seeing things. it is not then number of
> users that matters, but the number publications that are done
> correctly and properly.
> if you read my mail correctly, you should have seen that i do not want
> to demotivate you, but rather do the opposite. go to your adviser and
> stand up for your needs. insisting to do something without knowing
> what you are doing and without the proper training using an
> inefficient communication medium (e-mail) is something that you do to
> yourself and if that is demotivating and frustrating for you, then
> this is *your* fault, not anybody else's.
>> 3. NAMD should provide all the relevant solution for the users in both the commercial and academic versions because I am not in condition to purchase the software, that means I can't do the things, but I want to the MDS and want to build the force field for my molecule.
> no. this is a ridiculous demand. please read the link that kenno
> provided. on top of that, your problems are not at all NAMD specific
> problems, but general MD problems and it is *not* the task of NAMD
> developers to provide the information and training how to do MD in
> general. why not demand this training from the charmm folks, or the
> amber folks, or the gromacs folks or the materials studio folks or the
> macromodel folks or anybody else that provides an MD code.
>> 4. I want to know how to do this possible task in your way, and as you mentioned about the training I request you to please help me out for the training thing, I will be lucky to get training under your supervision.
> this is the job of your adviser not mine. your adviser gets paid for
> it and i am not.
>> regards
>> Abhishek
>> ________________________________________
>> From: <> on behalf of Axel Kohlmeyer <>
>> Sent: Wednesday, July 23, 2014 12:14 AM
>> To: Kenno Vanommeslaeghe
>> Cc:
>> Subject: Re: namd-l: Force field design
>> On Tue, Jul 22, 2014 at 11:40 AM, Kenno Vanommeslaeghe
>> <> wrote:
>>> Dear Abishek,
>>> In that case, you should try to make your prof read this:
>>> He or she basically gave you an impossible task. I don't want to discourage
>> i would not only call this an impossible task, but also outright
>> irresponsible behavior of the PI. not only to his student, but the
>> community in general. i can only encourage students to own up to this
>> and *demand* to be properly trained. it is not the job of the
>> community to compensate for this, especially when this is piled on top
>> of software and parameters that are provided at no cost and contain
>> the collected knowledge and experience of many, many people. PIs
>> exhibiting such irresponsible behavior should be named in public so
>> that a) students are made aware of the risk they may be taking and b)
>> their publications including simulation data, can be put under
>> particularly close scrutiny, since they are likely to be faulty and
>> misinterpreted.
>> axel.
>>> you, but it's the truth. Even if after a lot of sweat and tears, you somehow
>>> succeed to get a result out of NAMD, it will be hard to make sure you
>>> avoided all the nontrivial pitfalls and your results are relevant.
>>> Cheers,
>>> Kenno.
>>> On 07/22/2014 06:33 AM, Abhishek TYAGI wrote:
>>>> Dear Kenno,
>>>> Thanyou for your detail reply and instructions, actually I am alone doing
>>>> work on NAMD in my lab, even in my university, my Prof do not have
>>>> subsequent understanding of NAMD and even I don't have so any interaction to
>>>> Post doc/RA or other students, therefore, I directly ask you for the
>>>> problem. I have to do it myself and try to understand the things and do them
>>>> carefully.
>>>> I hope in future you understand my situation.
>>>> regards
>>>> Abhishek
>>>> ________________________________________
>>>> From: <> on behalf of
>>>> Kenno Vanommeslaeghe <>
>>>> Sent: Monday, July 21, 2014 11:47 PM
>>>> To:
>>>> Subject: Re: namd-l: Force field design
>>>> Dear Abhishek,
>>>> This list is full of very knowledgeable people who are very good at
>>>> resolving people's errors, but even the greatest guru cannot help you if
>>>> you don't tell them what exactly your problem is.
>>>> Since I get the impression you're relatively new to this, allow me to link
>>>> you to CHARMM's "parameter set discussion" forum guide lines:
>>>> I'm NOT suggesting you ask your question there. The CHARMM forums are for
>>>> CHARMM problems and the regulars don't like it if you post VMD/NAMD
>>>> problems. For NAMD, this mailinglist it the correct support channel.
>>>> Rather, the reason I'm giving you this link is that most of the good
>>>> practices it outlines are valid in *any* technical community, including
>>>> this list. In a nutshell, you are advised to search the web, consult the
>>>> valid resources (tutorials, FAQs...), experiment a bit yourself and
>>>> consult your advisor/mentor/senior postdoc before asking a question. Then,
>>>> if you must ask a question, take plenty of time formulating it, thinking
>>>> of it from the point of view of the expert trying to answer it. Make it
>>>> concise but include all relevant information.
>>>> Good luck,
>>>> Kenno.
>>>> On 07/19/2014 08:44 AM, Abhishek TYAGI wrote:
>>>>> Dear Kenno,
>>>>> Thankyou for the suggestion, I had read all the information provided so
>>>>> far and gone through the links in detail. But still I have a silly question,
>>>>> right now I have a.mol2 file and I got CGenFF a.str file, and for psfgen If
>>>>> I use a.str file it shows error, therefore I used CHARM-GUI to get psf and
>>>>> pdb file, I tried doe quick md on C-GUI it gives some topology and prm file,
>>>>> I used them for my simulation and got error, and for other files top and prm
>>>>> I still confused how to proceed.
>>>>> regards
>>>>> Abhi
>>>>> ________________________________________
>>>>> From: <> on behalf of
>>>>> Kenno Vanommeslaeghe <>
>>>>> Sent: Thursday, July 17, 2014 1:24 AM
>>>>> To:
>>>>> Subject: Re: namd-l: Force field design
>>>>> On 07/15/2014 12:55 PM, Abhishek TYAGI wrote:
>>>>>> 1. I tried CGenFF and got a *.str file but the data in the file is
>>>>>> different from my input file i.e. mol2 file, the pdb format is different
>>>>>> from the *.str file.
>>>>> The str file contains a force field for your molecule, while the mol2 and
>>>>> pdb formats contain a geometry. How could the data not be different???
>>>>> The str file is a concatenated topology and parameter file. NAMD knows to
>>>>> ignore the topology section and can read the file as it is.
>>>>> I believe psfgen does the same (read the topology and ignore the
>>>>> parameters) though I'm less sure about that.
>>>>>> 2. I tried to get force field from swissparam website and received the
>>>>>> different file as *.par, *.top file, I tried MD on this field it runs
>>>>>> successful, but the question is that is this correct approach?
>>>>> It is strongly encouraged to search the archive before posting a
>>>>> question.
>>>>> If you had, you would have discovered the use of SwissParam for
>>>>> condensed-phase calculations is discouraged, and found advise on better
>>>>> ways to do it:
>>>>> Christopher Mayne's advice in this thread is sound.
>> --
>> Dr. Axel Kohlmeyer
>> College of Science & Technology, Temple University, Philadelphia PA, USA
>> International Centre for Theoretical Physics, Trieste. Italy.
> --
> Dr. Axel Kohlmeyer
> College of Science & Technology, Temple University, Philadelphia PA, USA
> International Centre for Theoretical Physics, Trieste. Italy.

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