Hi,<br>Several comments:<br>1, it seems you use NCPP pseudopotentials . Therefore , 40 Ry for enenrgy cutoff is not enough to get convergent results.<br>2, You can do alignment of so-called fermi level, which is meaningless since you deal with a semiconductor.<br>
3, Underestimation of energy gap is well accepted in LDA calculations.<br><br><br>Hope helps<br><br>Regards<br><br><div class="gmail_quote">On Fri, Aug 28, 2009 at 3:37 AM, nand <span dir="ltr"><<a href="mailto:rana_nand@yahoo.com">rana_nand@yahoo.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"><table border="0" cellpadding="0" cellspacing="0"><tbody><tr><td style="font-family: inherit; font-style: inherit; font-variant: inherit; font-weight: inherit; font-size: inherit; line-height: inherit; font-size-adjust: inherit; font-stretch: inherit;" valign="top">
<br><br>Sir,<br>I am a research scholar at the Ranchi university, India. It will be a
great help if you can help me with the band structure calculation for
GaAs using Quantum Espresso.<br>
I do not get the correct band structure even with the input file you mentioned below. I am attaching the band structure pdf file which I
produced using input file given below. As you can see that the fermi level is
wrongly located and the band gap is badly underestimated. Please tell
me about the possible fault(s) possible in my calculation.<br>
Thanking you in advance.<br><font color="#888888">Nand Rana,<br>(Research Scholar)<br>Ranchi, India. </font><br><pre>-----------------------------------<br>input file for the scf calculation:<br><br>&control<br> calculation='scf',<br>
outdir='./tmp',<br> prefix='gaas',<br> pseudo_dir='/espresso-4.0.4/pseudo'<br>/<br><br>&system<br> ibrav=2,<br> celldm(1)=10.6827,<br> nbnd=8,<br> nat=2,<br> ntyp=2,<br> ecutwfc=40.0d0,<br>
occupations='fixed',<br> nspin=1<br>/<br><br>&electrons<br> conv_thr=1d-6,<br> mixing_beta=0.7,<br> diagonalization='david'<br>/<br><br>ATOMIC_SPECIES<br> Ga 69.723 Ga.pz-bhs.UPF<br> As 74.92160 As.pz-bhs.UPF<br>
<br>ATOMIC_POSITIONS alat<br> Ga 0.0 0.0 0.0<br> As 0.25 0.25 0.25<br><br>K_POINTS automatic<br> 10 10 10 0 0 0<br><br></pre><br><br><br></td></tr></tbody></table><br>
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<br></blockquote></div><br><br clear="all"><br>-- <br>Hai-Ping Lan <br>Department of Electronics ,<br>Peking University , Bejing, 100871<br><a href="mailto:lanhaiping@gmail.com">lanhaiping@gmail.com</a>, <a href="mailto:hplan@pku.edu.cn">hplan@pku.edu.cn</a><br>