THERMOSTATs - PART 1

Teodoro Laino teodor... at gmail.com
Wed Sep 26 14:28:51 CEST 2007


Dear All,

this message regards the thermostats in cp2k.
In order to have different kind of thermostats and also to implement  
few new options (see Axel messages) it was necessary
to rewrite and clean part of the thermostats/barostat in cp2k.

At the moment no new features have been added. Most of the work sofar  
was only cleaning and reorganizing typo
in a modular way. This, unfortunately, created also few minor changes  
in the input file whenever you want to use
thermostat.
In particular the NOSE section so-far defined is not any longer into  
the MD section but now is contained in a
THERMOSTAT section. The new structure of the input file looks like:

&MD
    ENSEMBLE NVT

    &THERMOSTAT
        TYPE [..]
        REGION (MASSIVE // GLOBAL // MOLECULE)
        &NOSE
        &END
   &END

&END

As you may have noticed, there's a new keyword named REGION within  
the thermostat section that accounts for the
same definition of the old NHCOPT keyword. (This keyword has been  
deleted from the TOPOLOGY section where it
had really no meaning and overall does not exist anymore).

Same things apply for the Core-Shell Model and KG methods. For both a  
new section THERMOSTAT has been defined
with the same rule.
Anyway the full set of input files present in the cp2k/tests has been  
updated to the new code style.

I decided to commit this preliminary part mainly because the main  
changes on the input file have been done.
There should not be other modifications and all the work from now  
till we have really modular thermostats will
be totally hidden for users (i.e. thermostat input won't change..)

I know that input changes are quite annoying, because old input files  
are not back-compatible, but unfortunately
they are unavoidable whenever changes involve old part of the code  
non-modular. The hope is that in the future
the structure of the cp2k input will become more and more stable.

Next thing to come in few days:

(1) New thermostat based on the Canonical Sampling through velocity  
rescaling of G.Bussi
(2) Possibility to have a user-defined region for thermostats..

Will send you another message when these things will be in cvs.

Again my apologies for possible inconveniences,
Teo



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