<br><br><div class="gmail_quote">On Sat, Nov 6, 2010 at 8:50 AM, Nicola Marzari <span dir="ltr"><<a href="mailto:nicola.marzari@materials.ox.ac.uk">nicola.marzari@materials.ox.ac.uk</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
<div>On 11/6/10 10:18 AM, Stefano de Gironcoli wrote:<br>
> Dear Jie,<br>
> as Gabriele was saying constrained DFT is not implemented in PWscf:<br>
> it is not so easy to force occupation of specific atomic-like levels in<br>
> a plane-wave basis.<br>
<br>
Dear Nicola, Stefano, and Gabriele,</div></blockquote><div> </div><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;"><div>Thank you very much for your information,</div>
</blockquote><div> </div><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;"><div>One thing I would like to emphasis is that I want to constrain electron<br>
</div></blockquote><div> occupations of <span class="result-summary">Kohn-Sham orbitals instead of atomic-like levels. The <br> method is usually called Delta-scf DFT, <br></span></div><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
<div> </div></blockquote><div> Will this makes some differences in implementation ? <br> <br> Thanks in advance,<br><br> Jie <br></div><div><br> </div><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
Dear Jie,<br>
<br>
with Patrick Sit and Matteo Cococcioni we did implement constrained DFT<br>
in the cp code a few years ago - Patrick (cc'd here, now in Princeton)<br>
has a working version of the code (and hopefully it will at a certain<br>
point make it into the public distribution).<br>
<br>
At the end the procedure is similar to what Stefano has just described -<br>
one adds a penalty for occupation matrices on a chosen manifold<br>
that are different from a desired target - by making the penalty very<br>
large one can make it into an exact constraint, or one could impose<br>
directly a Lagrange multiplier.<br>
<br>
Any code that has a working version of DFT+U should be easy to<br>
modify to make it into constrained DFT - you change the orbitals<br>
onto which you make the projections, and add a penalty or a<br>
Lagrange multiplier to force approximately or exactly the constraint<br>
that you want.<br>
<br>
nicola<br>
<br>
<br>
<br>
<br>
PS: H.-L. Sit, M. Cococcioni, and N. Marzari, "Realistic, Quantitative<br>
Descriptions of Electron-Transfer Reactions: Diabatic Surfaces from<br>
First-Principles Molecular Dynamics," Phys. Rev. Lett. 97, 028303<br>
(2006).<br>
<br>
Sit P. H.-L., Cococcioni M., Marzari N. "Car-Parrinello molecular<br>
dynamics in the DFT+U formalism: Structure and energetics of solvated<br>
ferrous and ferric ions" Journal of Electroanalytical Chemistry 607,<br>
107-112, (2007)<br>
<font color="#888888">--<br>
----------------------------------------------------------------------<br>
Prof Nicola Marzari Department of Materials University of Oxford<br>
Chair of Materials Modelling Director, Materials Modelling Laboratory<br>
<a href="mailto:nicola.marzari@materials.ox.ac.uk">nicola.marzari@materials.ox.ac.uk</a> <a href="http://mml.materials.ox.ac.uk/NM" target="_blank">http://mml.materials.ox.ac.uk/NM</a><br>
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