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Re: [ESPResSo-users] Bjerrum Length for Explicit Solvent
From: |
Ulf Schiller |
Subject: |
Re: [ESPResSo-users] Bjerrum Length for Explicit Solvent |
Date: |
Sun, 6 Oct 2013 13:37:30 +0200 |
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Mozilla/5.0 (X11; Linux i686; rv:17.0) Gecko/20130805 Thunderbird/17.0.8 |
On 10/06/2013 11:22 AM, Peter Košovan wrote:
Similar trouble arises when we use point charges but replace the
continuum solvent with an explicit one. We can measure the dielectric
constant epsilon_model of our solvent model. This will probably differ
from the experimental value epsilon_exp since the model is not exact.
To my understanding, the solution is to adjust our bjerrum parameter
such that
1/epsilon_exp = 1/(epsilon_model * epsilon_bjerrum) where
epsilon_bjerrum is obtained by substituting the value of bjerrum
parameter we provided to Espresso into the common formula for Bjerrum
length.
To this end, I do not see inconsistency between what Stefan and Marcus
have written.
Btw: does anyone know how users of other software deal with the problem
that epsilon_model does not match epsilon_exp? Do they use corrections
to epsilon similar to what I described or simply ignore the difference?
Hi Peter,
I think this is a software-independent modeling question. The Bjerrum
length would be just one of potentially many input parameters of an
explicit water model. If you take a given model and adjust only the
Bjerrum length to match epsilon, it is not unlikely that you 'destroy'
some other property like the diffusivity. Basically, the whole set of
input parameters among with the degrees of freedom of the model have to
be tuned to get the right physics. If I remember correctly, some SPC
water models are able to reproduce the dielectric constant.
Best,
Ulf
--
Dr. Ulf D. Schiller Building 04.16, Room 3006
Institute of Complex Systems (ICS-2) Phone: +49 2461 61-6144
Forschungszentrum Jülich, Germany Fax: +49 2461 61-3180
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- [ESPResSo-users] Bjerrum Length for Explicit Solvent, Jezreel Castillo, 2013/10/05
- Re: [ESPResSo-users] Bjerrum Length for Explicit Solvent, Markus Deserno, 2013/10/05
- Re: [ESPResSo-users] Bjerrum Length for Explicit Solvent, Stefan Kesselheim, 2013/10/05
- Re: [ESPResSo-users] Bjerrum Length for Explicit Solvent, Jezreel Castillo, 2013/10/05
- Re: [ESPResSo-users] Bjerrum Length for Explicit Solvent, Markus Deserno, 2013/10/05
- Re: [ESPResSo-users] Bjerrum Length for Explicit Solvent, Stefan Kesselheim, 2013/10/06
- Re: [ESPResSo-users] Bjerrum Length for Explicit Solvent, Peter Košovan, 2013/10/06
- Re: [ESPResSo-users] Bjerrum Length for Explicit Solvent, Stefan Kesselheim, 2013/10/06
- Re: [ESPResSo-users] Bjerrum Length for Explicit Solvent, Ulf Schiller, 2013/10/06
- Re: [ESPResSo-users] Bjerrum Length for Explicit Solvent,
Ulf Schiller <=
- Re: [ESPResSo-users] Bjerrum Length for Explicit Solvent, Markus Deserno, 2013/10/06
- Re: [ESPResSo-users] Bjerrum Length for Explicit Solvent, Stefan Kesselheim, 2013/10/06
- Re: [ESPResSo-users] Bjerrum Length for Explicit Solvent, Markus Deserno, 2013/10/06