[Pw_forum] temperature dependent density functional theory

[Axel Kohlmeyer]

> >  what "Temperature dependent DFT" would encompass.
> 
> In  my mind, all the first principles/ab initio calculations only work
> under  0K,  so I want to know whether can I do the first principles/ab
> initio calculations under other temperatures other than 0K, especially
> under some temperatures around room temperature?

first of all, the way people talk about ab initio being calculations
at OK usually has to be seen in the context of geometry optimizations.
this approach generally uses the time independent DFT formalism and
thus the Born-Oppenheimer approximation and with in that approximation
you can very well do molecular dynamics, i.e. a system at temperature
different from OK. you can do this with pw.x but also in cp.x using
the car-parrinello hamiltonian.

of course there is the effect of temperature to the electronic
structure, but that is is generally very small, unless you go 
to very high temperatures. this can be treated as well, but require
some more complicated to use methods. in most cases, you should be
just fine by applying a finite temperature to your atoms and using
normal DFT.

cheers,
   axel.

> 
> Kind regards,

-- 
=======================================================================
Axel Kohlmeyer   akohlmey at cmm.chem.upenn.edu   http://www.cmm.upenn.edu
   Center for Molecular Modeling   --   University of Pennsylvania
Department of Chemistry, 231 S.34th Street, Philadelphia, PA 19104-6323
tel: 1-215-898-1582,  fax: 1-215-573-6233,  office-tel: 1-215-898-5425
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