Hello

To make better energy minimization procedures I read about thermostats and 
barostats. I understand the physical concepts and differences between global 
and local thermostats and the difference between Berendsen and Nose-Hoover 
thermostat. 

1.) 
Maybe this question is a little bit hairsplitting, but: This concepts of 
thermostats and barostats, is this Thermodynamics, is this Kinetics, is this 
statistical physics? What is it if I want to give this a name.

2.)
I read, that local thermostats, i.e. stochastic dynamics produce a NVT 
ensemble, which is a canonical ensemble and that this alway fulfills Ergodicity 
Theorem. About this I have following question: In my literature they said, that 
this means, that all degrees of freedom in the system are coupled strong enough 
each other. This confuses me. I learned, that ergodicity means, that the 
complete phase space is passed by a trajectory, if we wait long enough. This 
means, that ensemble average is equal to time average of the system. Where is 
in my statement about ergodicity the meaning of "all degrees of freedom in the 
system are coupled strong enough" Do this in fact mean, that the complete phase 
space is passed?

3.)
I ask myself what I should use. First question: Local or global thermostat? I 
guess (not knowing, guessing), that global is better for energy minimization, 
because as far as I understand, it is more stable than local description. From 
a physical point of view I think Nose-Hoover shoul be always better, because it 
produces a real canonical ensemble, while Berendsen is microcanonical ensemble, 
which is totaly unrealistic?! In an microcanonical ensemble, energy is not 
changed with the enviroment. This makes no sense? 

Thanks for helping me
Greetings
Lara

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