<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div>Dear Sreekar,</div><div><br></div><div>I would first try to reduce mixing_beta and also lambda (say, to 0.2 or 0.1). You can then restart the calculation with a larger value of lambda.</div><div><br></div><div>Don't forget that for USPP you need to specify also ecutrho, and perhaps you don't need such a high ecutwfc.</div><div>If your USPPs are those on the QE website, I would use ecutwfc=35 and ecutrho=350, for instance.</div><div><br></div><div><br></div><br><div><div>Il giorno 25/ago/2011, alle ore 12.25, sreekar guddeti ha scritto:</div><br class="Apple-interchange-newline"><blockquote type="cite"><meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">Respected Sir/Madam,<br>1. I would like to perform a constrained magnetization calculation for a system, whose unconstrained spin polarized calculation gives an antiferromagnetic state, to converge at the ferromagnetic state.<br>
2. The system is a zigzag graphene nanoribbon(<cite><b><a href="http://en.wikipedia.org/wiki/Graphene">http://en.wikipedia.org/wiki/Graphene</a></b><b></b></cite><span class="gl"></span>) and I would like to flip the atomic moment at one of the edge site and constrain both the edge site moments.<br>
3. I calculated the antiferromagnetic edge site moment using PDOS calculation. I used 'lambda' parameter to constrain the moments.<br><br>4.Questions: Is 3) the right way to do it? If yes, what should be value of lambda? I used lambda =1 and the scf output (given below) is disturbing... I would like to ask what does "constrained moment : -20.000000" </blockquote><div><br></div><div>Indeed this looks suspicious... one should look into the code to understand what's going on. You can have a look into add_bfield.f90, it should not be very difficult to understand how it works.</div><div><br></div><div>Good luck</div><div><br></div><div><br></div><div>GS</div><div><br></div><br><blockquote type="cite">mean and why is the constrain energy so high. If it is not the right way, I would be grateful if you could suggest an alternative.<br>
<br>Thanking you,<br>Yours sincerely,<br>Sreekar Guddeti<br>Undergraduate (5th year)<br>Engineering Physics<br>IIT Bombay<br>India<br><br>PS: The system namelist for scf calculation and the sample output are given below and the complete input file is attached. <br>
<br><br>--------------------------------------<br>...<br> ==============================================================================<br> atom number 15 relative position : -3.5000 6.0622 0.0000<br> charge : 0.983302<br>
magnetization : 0.000256<br> magnetization/charge: 0.000260<br> constrained moment : 0.309100<br><br> ==============================================================================<br><br> ==============================================================================<br>
atom number 16 relative position : -3.0000 5.7735 0.0000<br> charge : 1.783674<br> magnetization : -0.385046<br> magnetization/charge: -0.215873<br> constrained moment : -20.000000<br>
<br> ==============================================================================<br>...<br>...<br><br><b>constraint energy</b> (Ryd) = 6095.83663339<br clear="all">---------------------------------<br><br><br><br>--------------------------------<br>
&SYSTEM<br> ibrav = 12,<br> celldm(1) = 4.608737,<br> celldm(2) = 12.0,<br> celldm(3) = 10.0,<br> celldm(4) = -0.50,<br> nat = 18,<br>
ntyp =10,<br> starting_magnetization(2)= 0.3091,<br> starting_magnetization(8)= 0.3091,<br> occupations='smearing',<br> smearing='gauss',<br>
degauss=0.01,<br> nspin=2,<br> constrained_magnetization='atomic'<br> lambda = 1<br> ecutwfc = 50.D0 ,<br> report = 2<br>
<br> /<br><br><br>-- <br>Sreekar Guddeti<br><br>
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<span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: medium; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: medium; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: medium; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: medium; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: medium; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: medium; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: medium; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div><span class="Apple-style-span" style="color: rgb(126, 126, 126); font-size: 16px; font-style: italic; "><br class="Apple-interchange-newline">§ Gabriele Sclauzero, EPFL SB ITP CSEA</span></div><div><font class="Apple-style-span" color="#7E7E7E"><i> PH H2 462, Station 3, CH-1015 Lausanne</i></font></div></div></span><br class="Apple-interchange-newline"></div></span><br class="Apple-interchange-newline"></div></span><br class="Apple-interchange-newline"></div></span><br class="Apple-interchange-newline"></div></span><br class="Apple-interchange-newline"></span><br class="Apple-interchange-newline"></span>
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