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Re: [ESPResSo-users] OPLS Parameters in ESPResSo
From: |
Axel Arnold |
Subject: |
Re: [ESPResSo-users] OPLS Parameters in ESPResSo |
Date: |
Wed, 07 Aug 2013 22:50:37 +0200 |
User-agent: |
Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:17.0) Gecko/20130620 Thunderbird/17.0.7 |
On 07.08.13 01:12, Jezreel Castillo wrote:
I would like to ask how to convert OPLS parameters to a form usable in
ESPResSo. For example, in dihedral angle interactions, OPLS has a four
phase equation, tied to a group of four particles, however in
ESPResSo, the equation is tied to a single particle within the
dihedral angle. Thank you.
Dear Jezreel,
in ESPResSo, any bond is tied to one particle, but can define an
interaction of several particles. For a dihedral, that are four
particles in total, just as in OPLS, which you specify when adding the
bond. For the order of the particles, please refer to the User's guide,
there is a picture explaining the order when calculating the angle from
these for particles.
Espresso's dihedral bond type corresponds to one of the OPLS Fourier
frequencies, so that you need in total four different dihedrals to model
a OPLS dihedral. Note that also the phases are alternating in the OPLS
definition, so that you need to change the phase. By comparing the OPLS
dihedral force with the Espresso expression, that is straight forward to
figure our.
Since Espresso is usually not used for atomistic modeling, I am not
aware of any ready OPLS setup.
Cheers,
Axel
--
JP Dr. Axel Arnold
ICP, Universität Stuttgart
Allmandring 3
70569 Stuttgart, Germany
Email: address@hidden
Tel: +49 711 685 67609