<div dir="ltr">Dear Professor Burton,<div><br></div><div>Thank you very much for the reply. Does that mean surface band should be doubly degenerate, whereas bulk bands are quadruply degnerate, otherwise how do we identify the surface state? In my calculated results, almost all bands are just doubly degenerate. </div>
<div><br></div><div>And from literature, the sign of spin moment in Gamma-M direction is opposite to that in Gmma-K direction, whereas, there is no any trend in my result.I also checked sigma(y) and sigma(z) component, there is also no trend. </div>
<div class="gmail_extra"><br><br><div class="gmail_quote">On Thu, Feb 20, 2014 at 10:56 AM, J. D. Burton <span dir="ltr"><<a href="mailto:jdburton1@gmail.com" target="_blank">jdburton1@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div lang="EN-US" link="blue" vlink="purple"><div><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Hi Peng,<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Each band is doubly-degenerate because your slab has two surfaces: A spin-polarized pair of bands for the top surface, and an oppositely-spin-polarized pair of bands for the bottom surface.<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Cheers,<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">J. D.<u></u><u></u></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">************************************<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">J. D. Burton, Ph.D.<u></u><u></u></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><a href="mailto:jdburton1@gmail.com" target="_blank"><span style="color:blue">jdburton1@gmail.com</span></a><u></u><u></u></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">************************************<u></u><u></u></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">"The job of a scientist is to generate wrong ideas as fast as possible."<u></u><u></u></span></p>
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<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> <a href="mailto:pw_forum-bounces@pwscf.org" target="_blank">pw_forum-bounces@pwscf.org</a> [mailto:<a href="mailto:pw_forum-bounces@pwscf.org" target="_blank">pw_forum-bounces@pwscf.org</a>] <b>On Behalf Of </b>Peng Chen<br>
<b>Sent:</b> Monday, February 17, 2014 8:11 PM<br><b>To:</b> PWSCF Forum<br><b>Subject:</b> [Pw_forum] Spin polarized surface band<u></u><u></u></span></p><div><div class="h5"><p class="MsoNormal"><u></u> <u></u></p><div>
<p class="MsoNormal">Hello Everyone,<u></u><u></u></p><div><p class="MsoNormal"><u></u> <u></u></p></div><div><p class="MsoNormal">Bi2Se3 slab with 6 quintuple layers is calculated. It is supposed to have spin polarized non-degenerate surface bands. However, in the calculated results, each band is doubly degenerated including surface band, as shown in the left panel of attached figure. And the spin components (sigma x) have opposite sign for degenerated surface band (S1). The input is listed below. I am not sure if I am doing the right thing. Any suggestions are welcome!<u></u><u></u></p>
<div><div><p class="MsoNormal"><u></u> <u></u></p></div><div><div><p class="MsoNormal">&control<u></u><u></u></p></div><div><p class="MsoNormal"> calculation='scf'<u></u><u></u></p></div><div><p class="MsoNormal">
wf_collect=.TRUE.<u></u><u></u></p></div><div><p class="MsoNormal"> restart_mode='from_scratch',<u></u><u></u></p></div><div><p class="MsoNormal"> prefix='BiSe.6QL.pbe.spin',<u></u><u></u></p></div>
<div><p class="MsoNormal"> pseudo_dir = '/data/espresso-5.0/pseudo/',<u></u><u></u></p></div><div><p class="MsoNormal"> outdir='/data/scratch/'<u></u><u></u></p></div><div><p class="MsoNormal"> /<u></u><u></u></p>
</div><div><p class="MsoNormal"> &system<u></u><u></u></p></div><div><p class="MsoNormal"> ibrav=4, celldm(1)=7.8196867, celldm(3)=17<u></u><u></u></p></div><div><p class="MsoNormal"> nat=30, ntyp=2,<u></u><u></u></p>
</div><div><p class="MsoNormal"> noncolin=.TRUE, lspinorb=.TRUE.<u></u><u></u></p></div><div><p class="MsoNormal"> starting_magnetization(1)=-0.1,<u></u><u></u></p></div><div><p class="MsoNormal"> ecutwfc = 60, ecutrho = 600,nbnd=360<u></u><u></u></p>
</div><div><p class="MsoNormal"> occupations='smearing', smearing='mv', degauss=0.015<u></u><u></u></p></div><div><p class="MsoNormal"> /<u></u><u></u></p></div><div><p class="MsoNormal"><u></u> <u></u></p>
</div><div><p class="MsoNormal"> &electrons<u></u><u></u></p></div><div><p class="MsoNormal"> conv_thr = 1.0e-7<u></u><u></u></p></div><div><p class="MsoNormal"> mixing_mode='local-TF'<u></u><u></u></p></div>
<div><p class="MsoNormal"> mixing_beta = 0.7<u></u><u></u></p></div><div><p class="MsoNormal"> /<u></u><u></u></p></div><div><div><p class="MsoNormal"><u></u> <u></u></p></div><div><p class="MsoNormal">ATOMIC_SPECIES<u></u><u></u></p>
</div><div><p class="MsoNormal"> Bi 208.98040 Bi.rel-pbe-dn-rrkjus_psl.1.0.0.UPF<u></u><u></u></p></div><div><p class="MsoNormal"> Se 78.96 Se.rel-pbe-n-rrkjus_psl.1.0.0.UPF<u></u><u></u></p></div><div><p class="MsoNormal">
<u></u> <u></u></p></div><div><p class="MsoNormal">ATOMIC_POSITIONS angstrom<u></u><u></u></p></div><div><p class="MsoNormal">Se 0 0 5.899840007<u></u><u></u></p></div><div><p class="MsoNormal">...... <u></u><u></u></p></div>
<div><p class="MsoNormal">Se 2.069 1.194537707 <a href="tel:60.92682666" value="+16092682666" target="_blank">60.92682666</a><u></u><u></u></p></div><div><p class="MsoNormal">K_POINTS (automatic)<u></u><u></u></p></div><div>
<p class="MsoNormal"> 10 10 1 0 0 0<u></u><u></u></p></div></div></div><div><p class="MsoNormal"><u></u> <u></u></p></div><div><p class="MsoNormal"><u></u> <u></u></p></div><p class="MsoNormal">-- <br> Best Regards.<br> Peng <u></u><u></u></p>
</div></div></div></div></div></div></div><br>_______________________________________________<br>
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<a href="http://pwscf.org/mailman/listinfo/pw_forum" target="_blank">http://pwscf.org/mailman/listinfo/pw_forum</a><br></blockquote></div><br><br clear="all"><div><br></div>-- <br><div dir="ltr"> Best Regards.<br> Peng <br>
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