Re: 1-5 Intramolecular repulsions

From: Jeffrey Potoff (jpotoffx_at_gmail.com)
Date: Wed Nov 05 2014 - 12:51:02 CST

Hi Rebecca,
I suspect I know what you are trying to do and it involves diols,
perhaps? My suggestion is to revise the model via by rescaling the 1-4
electrostatic interactions and/or refitting the dihedral potentials to
give you the conformational behavior that you are looking for. At least
if you want to run in NAMD...

-- 
======================================================================
Jeffrey J. Potoff                         jpotoff_at_wayne.edu
Professor and Director of Early Engineering Programs
Department of Chemical Engineering and Materials Science
Wayne State University			  5050 Anthony Wayne Dr
Detroit, MI 48202
http://potoff1.eng.wayne.edu              http://gomc.eng.wayne.edu
======================================================================
On 11/5/2014 1:33 PM, Kenno Vanommeslaeghe wrote:
> While the answer is in all likelihood "no", the question is poorly 
> formulated; I read it a few times over and I'm still confused about 
> what exactly you're looking for (and I work on force fields on a daily 
> basis). Do you mean "exceptions" instead of "interactions"? Also, if 
> you want an R^-12 repulsion without R^-6 attraction (which raises 
> questions about the rationale behind the force field), you also have 
> to worry about whether NAMD lets you specify them separately (I 
> honestly don't know). Finally, your "for example" link doesn't work; 
> it likely relies on form data that is not contained in the URL.
>
> On 11/05/2014 12:54 PM, Rebecca Lindsey wrote:
>> Dear All,
>>
>> Is there a way to include 1-5 (intramolecular) interactions in NAMD? As
>> far as I understand, neither NBFIX nor NBTABLE can be used to accomplish
>> this, as do not allow for a distinction between intra- and 
>> inter-molecular
>> interactions.
>>
>> The repulsion term in question would be along the lines of: E_repel =
>> a_repel/(r_ij)^12, as it is given by the TraPPE force field. (see, for
>> example: http://www.chem.umn.edu/groups/siepmann/trappe/molname.php)
>>
>> Thanks in advance for your insights.
>>
>> -- 
>> Rebecca K. Lindsey
>> ----------------------------------------------------
>> Ph. D. Candidate Website 
>> <https://sites.google.com/site/rebeccalindseycv/>
>> University of Minnesota LinkedIn
>> <http://www.linkedin.com/pub/rebecca-lindsey/17/b92/10>
>> Twin Cities r.lindsey78_at_gmail.com <mailto:r.lindsey78_at_gmail.com>
>> UMN Chemical Theory Center linds360_at_umn.edu <mailto:linds360_at_umn.edu>
>> ----------------------------------------------------
>

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