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Dear Gerhard,<br>
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<br>
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The optimized cell is;</div>
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R <span style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; line-height: normal;">
LATTICE,NONEQUIV.ATOMS: 1 166_R-3m </span>
<div><span style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; line-height: normal;">MODE OF CALC=RELA unit=ang
</span></div>
<div><span style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; line-height: normal;"> 8.591340 8.591340 22.415740 90.000000 90.000000120.000000</span></div>
<div><span style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; line-height: normal;">ATOM 1: X=0.23592070 Y=0.23592070 Z=0.23592070</span></div>
<div><span style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; line-height: normal;">ATOM 1:X= 0.76407930 Y=0.76407930 Z=0.76407930</span></div>
<div><span style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; line-height: normal;">Bi NPT= 781 R0=0.00000500 RMT= 2.5000 Z: 83.000</span></div>
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<span style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; line-height: normal;">with two atoms in the cell</span></div>
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<span style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; line-height: normal;">XYZ = A and 1-A</span><br>
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<span style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; line-height: normal;">A=0.23592070 and 1-A=0.76407930</span></div>
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<br>
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<span style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; line-height: normal;">When A is changed to 0.25;</span></div>
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<span style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; line-height: normal;">R LATTICE,NONEQUIV.ATOMS: 1 166_R-3m </span>
<div><span style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; line-height: normal;">MODE OF CALC=RELA unit=ang
</span></div>
<div><span style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; line-height: normal;"> 8.591340 8.591340 22.415740 90.000000 90.000000120.000000</span></div>
<div><span style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; line-height: normal;">ATOM 1: X=0.25000000 Y=0.25000000 Z=0.25000000</span></div>
<div><span style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; line-height: normal;">ATOM 1:X= 0.75000000 Y=0.75000000 Z=0.75000000</span></div>
<div><span style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; line-height: normal;">Bi NPT= 781 R0=0.00000500 RMT= 2.5000 Z: 83.000</span></div>
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<span style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; line-height: normal;">sgroup gives this warning;</span></div>
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<span style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; line-height: normal;"><small style="line-height: normal;">warning: !!! Unit cell has been reduced.
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</small><span style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; line-height: normal;"><small style="line-height: normal;">sgroup found: 166 (R -3 m)
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<small><br>
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<span style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; line-height: normal;"><small style="line-height: normal;">and the
</small></span><span style="font-size: 12pt; line-height: normal;"><small style="line-height: normal;">cell is reduced to;</small></span></div>
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<span style="font-size: 12pt; line-height: normal;"><small style="line-height: normal;">R LATTICE,NONEQUIV.ATOMS: 1 166 R-3m</small></span><small>
<div><span style="font-size: 12pt; line-height: normal;">MODE OF CALC=RELA unit=ang
</span></div>
<div><span style="font-size: 12pt; line-height: normal;"> 8.591340 8.591340 11.207870 90.000000 90.000000120.000000</span></div>
<div><span style="font-size: 12pt; line-height: normal;">ATOM 1: X=0.00000000 Y=0.00000000 Z=0.00000000</span></div>
<div><span style="font-size: 12pt; line-height: normal;">Bi1 NPT= 781 R0=0.00000500 RMT= 2.5000 Z: 83.0</span></div>
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<small>which is "semicubic" with an angle;<br>
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Angle is 87.539 deg</div>
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and only one Bi atom in the cell, now in the corners<br>
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And in this reduced Bi structure the "gap" at Ef in DOS disappears.</div>
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What I see is that with A=0.249 (0.25-0.001) and A=0.2499 (0.25-0.0001)<br>
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the DOS have a "gap" and they are quite symilar, but with the addition of the 0.0001 (A=0.25) the cel is reduced and the "gap" disappears.<br>
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I hope that this answers your questions and becomes clear what I am trying to show.<br>
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Saludos</div>
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Pablo<br>
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