[AMBER] Force-field with only Bond parameters

From: Stefano Motta <stefano.motta.unimib.it>
Date: Thu, 21 Nov 2019 11:04:44 +0100


I'm trying to use a force-field for TiO2, with only electrostatic, VdW, and
bond terms. I decided to create a mol2 file for the TiO2 nanoparticle (NP)
and treat the NP as a whole residue (the charges for the NP atoms are in
the mol2 file with the connectivity). Then I created an frcmod that
contains the mass, bonded and VdW parameters.

Anyway it seems that tleap is also searching for angle and dihedral term
(that I don't want to include) and gives me error. Then I included the
ANGLE and DIHE terms (putting them to 0) in the frcmod (all the missing
For example in case of angle, a lot of lines like this:
Ti6-Ot3-Ti6 0.0 0.0
and in case of dihedral, a lot of lines like this:
Ti6-Ot3-Ti6-Ot3 1 0.0 0.0 2.0

Covering all the possible combinations of Angle and dihedrals.
This resolved the problem for angle (tleap is not complaining about missing
parameters for angles) but not for dihedrals (I still get errors even for
dihedrals terms that I have inserted in the frcmod).

How can I solve this issue? Is there a way to disable the search for angle
and dihedral terms for this molecule?

Thanks in advance

Stefano Motta PhD
Email: stefano.motta.unimib.it <s.motta17.campus.unimib.it>
*Field of study:* Molecular Modeling, and Proteins Molecular Dynamics
Università degli Studi di Milano Bicocca
Department of Earth and Environmental Sciences
Piazza dell'Ateneo Nuovo, 1 - 20126, Milano (Italy).
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Received on Thu Nov 21 2019 - 02:30:02 PST
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