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I guess you don't need so strick condition for minimize the energy.<BR>
Wang. <BR>
material department of Kriss.<BR>
<BR>
> Message: 4<BR>> Date: Wed, 27 Aug 2008 21:52:19 -0400<BR>> From: "alan chen" <chenhanghuipwscf@gmail.com><BR>> Subject: [Pw_forum] vc-relax<BR>> To: pw_forum@pwscf.org<BR>> Message-ID:<BR>> <22ae3ca40808271852p36374a0evcda506434f22bdad@mail.gmail.com><BR>> Content-Type: text/plain; charset="iso-8859-1"<BR>> <BR>> Dear PWSCF users,<BR>> I try to relax the z-axis of STO while its x- and y-axis are fixed (i.e.<BR>> relax STO under strain). I use 'vc-relax' and cell_dofree=z. The<BR>> ion-dynamics is 'damp' and cell_dynamics is 'damp-w'. However I found that<BR>> this 'Wentzcovitch Damped Dynamics' always does 50 iterations and stops. But<BR>> the strain along the z direction is not necessarily the smallest after 50<BR>> iterations. Usually the z-strain is smallest after some iterations (for<BR>> example 30 iterations) then it goes up.<BR>> I want to ask why the code does not pick up the value of lattice<BR>> constant of z direction which minimizes the strain in the z direction but<BR>> just picks up the final value of lattice constant after 50 iterations?<BR>> Thank you very much.<BR>> <BR>> Hanghui Chen<BR>> Department of Physics<BR>> Yale University<BR><br /><hr />使用新一代 Windows Live Messenger 轻松交流和共享！ <a href='http://im.live.cn/' target='_new'>立刻下载！</a></body>
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