2014-01-26 Jakub Krajniak <[email protected]>:
>> (...)
>>
>> > And the convergence, I have add <post_add>convergence</post_add> so that
>> > I
>> > can measure the convergence.
>> > 4. What should be the optimal case for the convergence?
>> > What I am getting: (step_001: ~300, step_002: ~232, step_003: ~133) and
>> > then
>> > suddenly for step_004 it is ~8000.
>> > There was one step where the convergence was around 90.. but I run it
>> > for
>> > 100 steps and I don't see convergence at all.
>> > (I used the <initial_configuration>laststep option).
>> It seems something went wrong here, have a look at the different
>> distributions to see if one of them is completely off.
>> If so, you might need to scale the update and/or introduce an update
>> cycle in do_potential.
>>
>
> I have to ask about one more thing. I have noticed that when I am doing the
> cg simulation
> in NVE then the differences between target and new rdf are very small (well
> question is
> how to judge it, but it is around ~0.1). On the other hand the temperature
> in such
> simulation is very huge (I am running the atomistic one in in 298K with 1.0
> pressure).
> If I try to turn on the thermostat to keep the temperature in average
> constant then the differences
> in rdf are not stable and well again does not lead to some convergences.
> What should be a correct approach? I saw in the tutorials that the cg
> simulation are done
> by using the stochastic dynamics in the desire temperature. I don't
> understand then why I got so strange results.
The theory behind Boltzmann inversion assumes a Boltzmann distribution (NVT).
Which thermostat are you using? For Espresso++ Langevin thermostat
should to the same as stochastic dynamics.

>
> Other thing, what is exactly the purpose of update cycle in do_potential?
This option allows you to only update one interaction per iteration or
to separate IBI from the pressure correction update.
Let's say you have two types of particles, A and B, then you can set
do_update, 1 0 0 (A-A), 0 1 0 (B-B) and 0 0 1 (A-B) to separate the
updates.

Christoph

>
> Best, Jakub
>
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-- 
Christoph Junghans
Web: http://www.compphys.de

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