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[ESPResSo] Specification of External Potential/Force
From: |
Lorenzo Isella |
Subject: |
[ESPResSo] Specification of External Potential/Force |
Date: |
Tue, 19 Feb 2008 15:11:10 +0100 |
User-agent: |
Mozilla-Thunderbird 2.0.0.9 (X11/20080110) |
Dear All,
I think I have a quite unusual problem here.
I am often (ab)using Espresso to investigate systems and problems quite
far away from molecular dynamics.
Now, I would like to consider a system in 3D where you have a pair-wise
interaction between particles (not relevant right now, but you can think
of a Lennard-Jones potential) plus an external potential acting on the
system.
To fix the ideas, think of a strong harmonic confinement along z, i.e.
V_z=K_z*z^2 and of a much milder confining potential in the xy plane
i.e. V_{xy}=K_{xy}(x^2+y^2), with K_z>>K_{xy}.
This is intended to give rise to rather flat structures along along z
(together with an interaction potential having a hard-core repulsion).
(1) Is this doable in Espresso? Can one tune the external
force/interaction in a similar way as one can do with the tabulated
interaction potential?
In the documentation I bumped into:
[ext_force x value y value z value] An additional external force is
applied to
the particle.
when discussing particle properties, but I am not sure this allows me to
do exactly what I have in mind [See page 26 of the user guide].
(2) If I turn off the thermostat, am I using Espresso for deterministic
molecular dynamics? Am I then removing the "noise" (apart from numerical
round-off errors) from the simulation?
Many thanks
Lorenzo
- [ESPResSo] Specification of External Potential/Force,
Lorenzo Isella <=