Re: AMBER: Question bonds and angles in frcmod and lib files

From: Jennie Thomas <>
Date: Wed, 03 May 2006 10:26:55 -0700

Thanks for your comment, I do want to change all of the instances of the
atom types involved. I'm running a relatively simple system with only
one of this instance. However, simply setting the force constant to
zero doesn't seem to work due to this nnb,ntot problem.

I'm pretty sure these are related, because when I revert to using a .lib
file without the bonds (only angles defined) the minimization runs.


Bill Ross wrote:

>>>I'm trying to more completely understand the information contained in
>>>frcmod and lib files. I would like to change from using an angle to
>>>constrain the geometry of my molecule to using an artificial bond with a
>>>given force constant. I understand how to add a bond to both the lib
>>>file and to the frcmod file. However, I don't understand how to delete
>>>an angle from these files.
>>Generally, you effectively delete the angle term by (re-)defining that angle
>>potential with a force constant of zero.
>Be sure when modifying params that you intend to modify all instances
>of the atom types involved.
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Received on Thu May 04 2006 - 17:10:37 PDT
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