[Pw_forum] BO molecular dynamics

[Axel Kohlmeyer]

On Tue, 15 Jul 2008, Mansoureh Pashangpour wrote:

MP> Dear Axle
MP> At first I wanted to use CP molecular dynamics for my system but after that
MP> I found I couden't use it for metalic systems.so I must use born-oppenhiemer
MP> molecular dynamics.I think it needs to minmization like CP MD.do you think
MP> different?

what you have to do or not is not a matter of my opinion,
but of the requirements of the physics of your system (which is ?),
the accuracy of the results you want to achieve and the 
effort you want to invest.

please have a look at what is done to the wavefunction in CP 
dynamics and what is done in BO dynamics instead then you 
can answer this for yourself. this something you should know
_before_ starting _any_ of those calculations. for example 
the review by dominik marx and juerg hutter (listed on the QE
homepage somewhere under "learn") gives a good overview (it is 
a bit dated by now, there have been significant improvements, 
particularly in BO-dynamics since).

cheers,
   axel.



MP> good luck
MP> Mansoureh
MP> 
MP> On 7/15/08, Axel Kohlmeyer <akohlmey at cmm.chem.upenn.edu> wrote:
MP> >
MP> > On Tue, 15 Jul 2008, Mansoureh Pashangpour wrote:
MP> >
MP> > MP> Deal PWscf users
MP> > MP>
MP> > MP> I want to do minimization for Born-Oppenhiemer  molecular dynamics.
MP> > MP> which of these way is correct?
MP> >
MP> > please explain. what is "minimization for BO dynamics"?
MP> >
MP> >
MP> > both your input fragments don't make much sense as they
MP> > contain too little information...
MP> >
MP> > cheers,
MP> >   axel.
MP> >
MP> > MP>
MP> > MP>  dt =6.0d0,
MP> > MP> .
MP> > MP> .
MP> > MP> .
MP> > MP>  &electrons
MP> > MP>    emass = 500.d0,
MP> > MP>    emass_cutoff = 2.25d0,
MP> > MP>    orthogonalization = 'ortho',
MP> > MP>    electron_dynamics = 'damp',
MP> > MP>  /
MP> > MP>  &ions
MP> > MP>  ion_dynamics = 'none',
MP> > MP> /
MP> > MP> ---------------------------------
MP> > MP> dt =20.0d0,
MP> > MP> .
MP> > MP> .
MP> > MP> .
MP> > MP>  &electrons
MP> > MP>    emass = 500.d0,
MP> > MP>    emass_cutoff = 2.25d0,
MP> > MP>    orthogonalization = 'ortho',
MP> > MP>    electron_dynamics = 'cg',
MP> > MP>  /
MP> > MP>  &ions
MP> > MP>  ion_dynamics = 'none',
MP> > MP> /
MP> > MP> ----------------------------------
MP> > MP> I look forward to hearing from you.
MP> > MP> Thanks
MP> > MP> Mansoureh
MP> > MP>
MP> >
MP> > --
MP> > =======================================================================
MP> > Axel Kohlmeyer   akohlmey at cmm.chem.upenn.edu   http://www.cmm.upenn.edu
MP> >   Center for Molecular Modeling   --   University of Pennsylvania
MP> > Department of Chemistry, 231 S.34th Street, Philadelphia, PA 19104-6323
MP> > tel: 1-215-898-1582,  fax: 1-215-573-6233,  office-tel: 1-215-898-5425
MP> > =======================================================================
MP> > If you make something idiot-proof, the universe creates a better idiot.
MP> > _______________________________________________
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MP> >
MP> 

-- 
=======================================================================
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
=======================================================================
If you make something idiot-proof, the universe creates a better idiot.