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Dear all,</div>
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I have successfully produced the band structure of bulk Si using FCC lattice with 2 atoms per basis. The relevant input sections are as follows:</div>
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<span style="font-family: "Courier New", monospace; color: rgb(23, 78, 134);">&system</span><span><br>
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<div><span style="font-family: "Courier New", monospace; color: rgb(23, 78, 134);">ibrav=2,
</span><br>
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<div><span style="font-family: "Courier New", monospace; color: rgb(23, 78, 134);">celldm(1)=10.410909236,</span><br>
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<div><span style="font-family: "Courier New", monospace; color: rgb(23, 78, 134);">nat=2,
</span><br>
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<div><span style="font-family: "Courier New", monospace; color: rgb(23, 78, 134);">ntyp=1,</span><br>
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<div><span style="font-family: "Courier New", monospace; color: rgb(23, 78, 134);">nbnd=8</span><br>
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<div><span style="font-family: "Courier New", monospace; color: rgb(23, 78, 134);">/</span></div>
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<div><span style="font-family: "Courier New", monospace; color: rgb(23, 78, 134);">ATOMIC_POSITIONS (alat)</span><br>
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<div><span style="font-family: "Courier New", monospace; color: rgb(23, 78, 134);">Si 0.00 0.00 0.00</span><br>
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<span style="font-family: "Courier New", monospace; color: rgb(23, 78, 134);">Si 0.25 0.25 0.25</span></div>
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<span style="font-family: "Courier New", monospace; color: rgb(23, 78, 134);"></span><br>
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<div style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
However, when I try to get the same band structure using a SC unit cell that contain 8 Si atoms, I get completely wrong results. The relevant input sections are as follows:</div>
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<div style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<span style="font-family: "courier new", monospace; font-size: 12pt; color: rgb(23, 78, 134); background-color: rgba(0, 0, 0, 0);">&system</span><span><br>
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<div><span style="font-family: "courier new", monospace; font-size: 12pt; color: rgb(23, 78, 134); background-color: rgba(0, 0, 0, 0);">ibrav=1,
</span><br>
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<div><span style="font-family: "courier new", monospace; font-size: 12pt; color: rgb(23, 78, 134); background-color: rgba(0, 0, 0, 0);">celldm(1)=10.3557,</span><br>
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<div><span style="font-family: "courier new", monospace; font-size: 12pt; color: rgb(23, 78, 134); background-color: rgba(0, 0, 0, 0);">nat=8,
</span><br>
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<div><span style="font-family: "courier new", monospace; font-size: 12pt; color: rgb(23, 78, 134); background-color: rgba(0, 0, 0, 0);">ntyp=1,</span><br>
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<div><span style="font-family: "courier new", monospace; font-size: 12pt; color: rgb(23, 78, 134); background-color: rgba(0, 0, 0, 0);">nbnd=32</span><br>
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<div><span style="font-family: "courier new", monospace; font-size: 12pt; color: rgb(23, 78, 134); background-color: rgba(0, 0, 0, 0);">/</span><br>
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<div><br>
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<div><span style="font-family: "courier new", monospace; font-size: 12pt; color: rgb(23, 78, 134); background-color: rgba(0, 0, 0, 0);">ATOMIC_POSITIONS (alat)</span><br>
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<div><span style="font-family: "courier new", monospace; font-size: 12pt; color: rgb(23, 78, 134); background-color: rgba(0, 0, 0, 0);">Si 0 0 0</span><br>
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<div><span style="font-family: "courier new", monospace; font-size: 12pt; color: rgb(23, 78, 134); background-color: rgba(0, 0, 0, 0);">Si 0 0.5 0.5</span><br>
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<div><span style="font-family: "courier new", monospace; font-size: 12pt; color: rgb(23, 78, 134); background-color: rgba(0, 0, 0, 0);">Si 0.5 0.5 0</span><br>
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<div><span style="font-family: "courier new", monospace; font-size: 12pt; color: rgb(23, 78, 134); background-color: rgba(0, 0, 0, 0);">Si 0.5 0 0.5</span><br>
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<div><span style="font-family: "courier new", monospace; font-size: 12pt; color: rgb(23, 78, 134); background-color: rgba(0, 0, 0, 0);">Si 0.75 0.25 0.75</span><br>
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<div><span style="font-family: "courier new", monospace; font-size: 12pt; color: rgb(23, 78, 134); background-color: rgba(0, 0, 0, 0);">Si 0.25 0.25 0.25</span><br>
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<div><span style="font-family: "courier new", monospace; font-size: 12pt; color: rgb(23, 78, 134); background-color: rgba(0, 0, 0, 0);">Si 0.25 0.75 0.75</span><br>
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<div><span style="font-family: "courier new", monospace; font-size: 12pt; color: rgb(23, 78, 134); background-color: rgba(0, 0, 0, 0);">Si 0.75 0.75 0.25</span></div>
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<div><span style="font-family: calibri, helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0); background-color: rgba(0, 0, 0, 0);">Both calculations use the same special k-points</span><span style="font-family: "courier new", monospace; font-size: 12pt; color: rgb(23, 78, 134); background-color: rgba(0, 0, 0, 0);"></span><span style="font-family: calibri, helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0); background-color: rgba(0, 0, 0, 0);">.
The resulting band structures (the correct one and the wrong one) are attached. So what am I doing wrong?<br>
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<div><span style="font-family: calibri, helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0); background-color: rgba(0, 0, 0, 0);">Thanks in advance<br>
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