<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><br><div><div>On Jun 12, 2013, at 9:38 AM, Yue-Wen Fang wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div dir="ltr"><span style="color:rgb(0,0,0);font-family:verdana,tahoma,arial,helvetica,sans-serif;font-size:12px;background-color:rgb(227,225,225)">i have two urgent problems. </span><br style="color:rgb(0,0,0);font-family:verdana,tahoma,arial,helvetica,sans-serif;font-size:12px">
<span style="color:rgb(0,0,0);font-family:verdana,tahoma,arial,helvetica,sans-serif;font-size:12px;background-color:rgb(227,225,225)">One is that, when i make scf calculation of LAO/STO superlattice for different kmesh, they got different fermi levers as well as the total energy. </span><br style="color:rgb(0,0,0);font-family:verdana,tahoma,arial,helvetica,sans-serif;font-size:12px">
<span style="color:rgb(0,0,0);font-family:verdana,tahoma,arial,helvetica,sans-serif;font-size:12px;background-color:rgb(227,225,225)">below is some results. </span><br style="color:rgb(0,0,0);font-family:verdana,tahoma,arial,helvetica,sans-serif;font-size:12px">
<span style="color:rgb(0,0,0);font-family:verdana,tahoma,arial,helvetica,sans-serif;font-size:12px;background-color:rgb(227,225,225)">12*8*1 TOTEN = -348.979566 eV E-fermi : 4.7215 </span><br style="color:rgb(0,0,0);font-family:verdana,tahoma,arial,helvetica,sans-serif;font-size:12px">
<span style="color:rgb(0,0,0);font-family:verdana,tahoma,arial,helvetica,sans-serif;font-size:12px;background-color:rgb(227,225,225)">12*8*2 TOTEN = -348.98343746 eV E-fermi : 4.7500 </span><br style="color:rgb(0,0,0);font-family:verdana,tahoma,arial,helvetica,sans-serif;font-size:12px">
<span style="color:rgb(0,0,0);font-family:verdana,tahoma,arial,helvetica,sans-serif;font-size:12px;background-color:rgb(227,225,225)">12*8*4 TOTEN = -347.52711583 eV E-fermi : 7.3118 </span><br style="color:rgb(0,0,0);font-family:verdana,tahoma,arial,helvetica,sans-serif;font-size:12px">
<span style="color:rgb(0,0,0);font-family:verdana,tahoma,arial,helvetica,sans-serif;font-size:12px;background-color:rgb(227,225,225)">it's very strange they are so different, so i cannot belive in them. </span><br style="color:rgb(0,0,0);font-family:verdana,tahoma,arial,helvetica,sans-serif;font-size:12px">
<br style="color:rgb(0,0,0);font-family:verdana,tahoma,arial,helvetica,sans-serif;font-size:12px"><span style="color:rgb(0,0,0);font-family:verdana,tahoma,arial,helvetica,sans-serif;font-size:12px;background-color:rgb(227,225,225)">The other question is that, after scf calculation on 12*8*2, i make a dos calculation, and find that the fermi energy is shifted from </span><span style="font-family:verdana,tahoma,arial,helvetica,sans-serif;font-size:12px;color:blue">4.7500 in scf to 7.4184 in dos</span><span style="color:rgb(0,0,0);font-family:verdana,tahoma,arial,helvetica,sans-serif;font-size:12px;background-color:rgb(227,225,225)">. i also ploted the density of state in scf and dos calculation, former states insulator and latter is a metal phase. so ridiculous. </span><br clear="all">
<div><br></div>-- <br>------------------------------------------------------------------------------------------------------------<div>Yue-Wen FANG, PhD candidate<br><div><a href="http://clpm.ecnu.edu.cn/" style="font-family:arial,sans-serif;font-size:14px;background-color:rgb(255,255,255)" target="_blank">Key Laboratory of Polar Materials and Devices, Ministry of Education</a><br style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:14px;background-color:rgb(255,255,255)">
<div style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:14px;background-color:rgb(255,255,255)"><a href="http://www.ecnu.edu.cn/english/" target="_blank">East China Normal University</a> </div><div style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:14px;background-color:rgb(255,255,255)">
I will persist until I succeed!</div></div><div><br></div></div></div></blockquote><br></div><div>As you write in your signature ("I will persist until I succeed") maybe you should persist in trying to understanding why QE is giving you right answers to</div><div>wrong questions. I mean that, provided your input has not syntax errors, QE will always output a total energy or a Fermi energy. Whether or not those</div><div>energies are the right ones and have a physical meaning depends on how you are performing the calculation.</div><div><br></div><div>I cannot say so much if you do not provide an input, but, based on your data:</div><div><br></div>1) your k meshes differ by the value of the number of k-points along the z direction (12x8x1, 12x8x2, 12x8x4). Any quantity you compute would be independent of this number<div>**ONLY IF** you expect that NO dispersion occurs along the z direction. When no dispersion occurs along the z-direction? If you are really dealing with</div><div>a superlattice, let's say an A-B-A-B-A-B-.... stacking, you supercell contains an A-B unit. Now, such unit is periodically repeated along the z-direction,</div><div>according to the Bravais lattice you specify in input. Let's call c the lattice parameter along the z direction. The distance between two periodic replicas</div><div>of the A subunit is c. If c is sufficiently large, then you results might appear strange and the explanation should be found elsewhere. But if c is just few A,</div><div>than there is interaction between periodic replicas along the z direction. As such, dispersion would occur, and sampling the BZ along the Z direction with</div><div>just one k-point would provide not-converged results.</div><div><br></div><div>2) DOS calculations usually require k-meshes larger or much larger that those you need to converge the charge density in you scf calculation. If you look,</div><div>for example, to espresso-5.0.2/PP/examples/example02, where the DOS of Ni is computed, the scf calculation is performed with 60 k points, but the DOS using</div><div>a 12x12x12 grid. How are you performing your DOS calculations? And what does it mean "density of state in scf and dos calculation"? The DOS is computed only</div><div>after an "nscf" calculation following the scf.</div><div><br></div><div>3) If your system is metallic, than you need also to specify a smearing to help the system in converging with respect to the k-point grid. Also this parameter must be</div><div>carefully checked.</div><div><br></div><div>I suggest you to first check the convergence of your scf calculation with respect the k-point grid and any other calculation parameter you think might be relevant.</div><div>Then perform the DOS calculation, according to the right procedure. With just some patience, you can easily change your results from ridiculous to reasonable.</div><div><br></div><div>Giovanni</div><div><br></div><div><div>
<span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-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; font-size: medium; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; 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; font-size: medium; "><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><br class="Apple-interchange-newline"><br></div><div><br></div><div>--</div><div><div><br></div><div>**** PLEASE NOTICE THE NEW E-MAIL ADDRESS: <a href="mailto:giovanni.cantele@spin.cnr.it">giovanni.cantele@spin.cnr.it</a></div></div><div><br></div><div><div>Giovanni Cantele, PhD</div><div>CNR-SPIN</div><div>c/o Dipartimento di Scienze Fisiche</div><div>Universita' di Napoli "Federico II"</div><div>Complesso Universitario M. S. Angelo - Ed. 6</div><div>Via Cintia, I-80126, Napoli, Italy</div><div>Phone: +39 081 676910</div><div>Skype contact: giocan74</div><div><br></div><div>ResearcherID: <a href="http://www.researcherid.com/rid/A-1951-2009">http://www.researcherid.com/rid/A-1951-2009</a></div><div>Web page: <a href="http://people.na.infn.it/~cantele">http://people.na.infn.it/~cantele</a></div><div> <a href="http://www.nanomat.unina.it">http://www.nanomat.unina.it</a></div></div></span></div></span></div></span></div></span></span>
</div>
<br></div></body></html>