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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Hi Peng,<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></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.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Cheers,<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>J. D.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>************************************<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>J. D. Burton, Ph.D.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><a href="mailto:jdburton1@gmail.com"><span style='color:blue'>jdburton1@gmail.com</span></a><o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Research Assistant Professor<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>University of Nebraska Lincoln<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Physics and Astronomy<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Office Ph. (402) 472 2499<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Mobile Ph. (402) 419 9918<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>310A Jorgensen Hall<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Verdana","sans-serif";color:black'>CV: <a href="http://tinyurl.com/2avltsc"><span style='color:blue'>http://tinyurl.com/2avltsc</span></a></span><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>************************************<o:p></o:p></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."<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>-- Murray Gell-Mann<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><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"'> pw_forum-bounces@pwscf.org [mailto:pw_forum-bounces@pwscf.org] <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<o:p></o:p></span></p><p class=MsoNormal><o:p> </o:p></p><div><p class=MsoNormal>Hello Everyone,<o:p></o:p></p><div><p class=MsoNormal><o:p> </o:p></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!<o:p></o:p></p><div><div><p class=MsoNormal><o:p> </o:p></p></div><div><div><p class=MsoNormal>&control<o:p></o:p></p></div><div><p class=MsoNormal> calculation='scf'<o:p></o:p></p></div><div><p class=MsoNormal> wf_collect=.TRUE.<o:p></o:p></p></div><div><p class=MsoNormal> restart_mode='from_scratch',<o:p></o:p></p></div><div><p class=MsoNormal> prefix='BiSe.6QL.pbe.spin',<o:p></o:p></p></div><div><p class=MsoNormal> pseudo_dir = '/data/espresso-5.0/pseudo/',<o:p></o:p></p></div><div><p class=MsoNormal> outdir='/data/scratch/'<o:p></o:p></p></div><div><p class=MsoNormal> /<o:p></o:p></p></div><div><p class=MsoNormal> &system<o:p></o:p></p></div><div><p class=MsoNormal> ibrav=4, celldm(1)=7.8196867, celldm(3)=17<o:p></o:p></p></div><div><p class=MsoNormal> nat=30, ntyp=2,<o:p></o:p></p></div><div><p class=MsoNormal> noncolin=.TRUE, lspinorb=.TRUE.<o:p></o:p></p></div><div><p class=MsoNormal> starting_magnetization(1)=-0.1,<o:p></o:p></p></div><div><p class=MsoNormal> ecutwfc = 60, ecutrho = 600,nbnd=360<o:p></o:p></p></div><div><p class=MsoNormal> occupations='smearing', smearing='mv', degauss=0.015<o:p></o:p></p></div><div><p class=MsoNormal> /<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal> &electrons<o:p></o:p></p></div><div><p class=MsoNormal> conv_thr = 1.0e-7<o:p></o:p></p></div><div><p class=MsoNormal> mixing_mode='local-TF'<o:p></o:p></p></div><div><p class=MsoNormal> mixing_beta = 0.7<o:p></o:p></p></div><div><p class=MsoNormal> /<o:p></o:p></p></div><div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>ATOMIC_SPECIES<o:p></o:p></p></div><div><p class=MsoNormal> Bi 208.98040 Bi.rel-pbe-dn-rrkjus_psl.1.0.0.UPF<o:p></o:p></p></div><div><p class=MsoNormal> Se 78.96 Se.rel-pbe-n-rrkjus_psl.1.0.0.UPF<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>ATOMIC_POSITIONS angstrom<o:p></o:p></p></div><div><p class=MsoNormal>Se 0 0 5.899840007<o:p></o:p></p></div><div><p class=MsoNormal>...... <o:p></o:p></p></div><div><p class=MsoNormal>Se 2.069 1.194537707 60.92682666<o:p></o:p></p></div><div><p class=MsoNormal>K_POINTS (automatic)<o:p></o:p></p></div><div><p class=MsoNormal> 10 10 1 0 0 0<o:p></o:p></p></div></div></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><p class=MsoNormal>-- <br> Best Regards.<br> Peng <o:p></o:p></p></div></div></div></div></body></html>