[ESPResSo] Specification of External Potential/Force

[Lorenzo Isella]

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