[Pw_forum] Pw_forum Digest, Vol 14, Issue 49

wangqiang thefarsky at hotmail.com
Thu Aug 28 08:43:55 CEST 2008

I guess you don't need so strick condition for minimize the energy.
material department of Kriss.
> Message: 4> Date: Wed, 27 Aug 2008 21:52:19 -0400> From: "alan chen" <chenhanghuipwscf at gmail.com>> Subject: [Pw_forum] vc-relax> To: pw_forum at pwscf.org> Message-ID:> <22ae3ca40808271852p36374a0evcda506434f22bdad at mail.gmail.com>> Content-Type: text/plain; charset="iso-8859-1"> > Dear PWSCF users,> I try to relax the z-axis of STO while its x- and y-axis are fixed (i.e.> relax STO under strain). I use 'vc-relax' and cell_dofree=z. The> ion-dynamics is 'damp' and cell_dynamics is 'damp-w'. However I found that> this 'Wentzcovitch Damped Dynamics' always does 50 iterations and stops. But> the strain along the z direction is not necessarily the smallest after 50> iterations. Usually the z-strain is smallest after some iterations (for> example 30 iterations) then it goes up.> I want to ask why the code does not pick up the value of lattice> constant of z direction which minimizes the strain in the z direction but> just picks up the final value of lattice constant after 50 iterations?> Thank you very much.> > Hanghui Chen> Department of Physics> Yale University
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