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<div>Professor Blaha, Israel,<br>
</div>
<div></div>
<div>The following suggestion does not work;</div>
<div>-----------------------------------<br>
</div>
<div>No. You should not run a supercell for a R structure, since this will <br>
</div>
<div><font size="2"><span style="font-size:11pt">
<div>even with 1x1x1 create a 3 times (conventional hexagonal) cell.<br>
Instead,<br>
i) remove the spacegroup and change to "R"-lattice.<br>
ii) split the 4 Fe positions into 2 and 2 (Fe1 and Fe2). This splitting <br>
can be done in different ways (up-up-dn-dn along z; or in other ways. <br>
Please check literature which one is correct). After nn (or sgroup) you <br>
should have only 2 Fe positions.</div>
<div>-----------------------------------</div>
<div>The original cell is;</div>
<div><br>
</div>
<div><span>Title <br>
</span>
<div>R LATTICE,NONEQUIV.ATOMS: 2 167_R-3c <br>
</div>
<div>MODE OF CALC=RELA unit=ang <br>
</div>
<div> 9.519310 9.519310 26.005287 90.000000 90.000000120.000000<br>
</div>
<div>ATOM -1: X=0.35500000 Y=0.35500000 Z=0.35500000<br>
</div>
<div>ATOM -1:X= 0.64500000 Y=0.64500000 Z=0.64500000<br>
</div>
<div>ATOM -1:X= 0.85500000 Y=0.85500000 Z=0.85500000<br>
</div>
<div>ATOM -1:X= 0.14500000 Y=0.14500000 Z=0.14500000<br>
</div>
<div>Fe NPT= 781 R0=0.00005000 RMT= 2.0000 Z: 26.000<br>
</div>
<div><br>
</div>
<div>ATOM 2: X=0.94499999 Y=0.55500000 Z=0.25000000<br>
</div>
<div>ATOM 2:X= 0.05500001 Y=0.44500000 Z=0.75000000<br>
</div>
<div>ATOM 2:X= 0.55500000 Y=0.25000000 Z=0.94499999<br>
</div>
<div>ATOM 2:X= 0.44500000 Y=0.75000000 Z=0.05500001<br>
</div>
<div>ATOM 2:X= 0.25000000 Y=0.94499999 Z=0.55500000<br>
</div>
<div>ATOM 2:X= 0.75000000 Y=0.05500001 Z=0.44500000<br>
</div>
<div>O NPT= 781 R0=0.00010000 RMT= 2.0000 Z: 8.000<br>
</div>
<span></span></div>
<div>.................................<br>
</div>
<div>but if space group 167 is changed to R the cell is changed to</div>
<div>.................................</div>
<div><span>Title <br>
</span>
<div>R LATTICE,NONEQUIV.ATOMS: 2 <br>
</div>
<div>MODE OF CALC=RELA unit=ang <br>
</div>
<div> 9.519310 9.519310 26.005287 90.000000 90.000000120.000000<br>
</div>
<div>ATOM -1: X=0.00000000 Y=0.00000000 Z=0.35500000<br>
</div>
<div>ATOM -1:X= 0.64500000 Y=0.64500000 Z=0.64500000<br>
</div>
<div>ATOM -1:X= 0.85500000 Y=0.85500000 Z=0.85500000<br>
</div>
<div>ATOM -1:X= 0.14500000 Y=0.14500000 Z=0.14500000<br>
</div>
<div>Fe NPT= 781 R0=0.00005000 RMT= 2.0000 Z: 26.000<br>
</div>
<div><br>
</div>
<div>ATOM 2: X=0.97166667 Y=0.33333333 Z=0.58333333<br>
</div>
<div>ATOM 2:X= 0.05500001 Y=0.44500000 Z=0.75000000<br>
</div>
<div>ATOM 2:X= 0.55500000 Y=0.25000000 Z=0.94499999<br>
</div>
<div>ATOM 2:X= 0.44500000 Y=0.75000000 Z=0.05500001<br>
</div>
<div>ATOM 2:X= 0.25000000 Y=0.94499999 Z=0.55500000<br>
</div>
<div>ATOM 2:X= 0.75000000 Y=0.05500001 Z=0.44500000<br>
</div>
<div>O NPT= 781 R0=0.00010000 RMT= 2.0000 Z: 8.000<font size="2"><span>
<div><span></span></div>
<div>.................................</div>
</span></font><font size="2"><span>
<div>
<div>but if instead one changes 167 to P, but the cell parameters are changed to
<br>
</div>
<div> 10.263863 10.263863 10.263863 55.256000 55.256000 55.256000</div>
<div>then the cell has all the characteristics of the original but the Fe can be split into 'up' and 'dn'<br>
</div>
<span></span></div>
<div>.................................</div>
</span></font><span>Title </span>
<br>
<span></span></div>
<div>P LATTICE,NONEQUIV.ATOMS: 2 <br>
</div>
<div>MODE OF CALC=RELA unit=ang <br>
</div>
<div> 10.263863 10.263863 10.263863 55.256000 55.256000 55.256000<br>
</div>
<div>ATOM -1: X=0.35500000 Y=0.35500000 Z=0.35500000<br>
</div>
<div>ATOM -1:X= 0.64500000 Y=0.64500000 Z=0.64500000<br>
</div>
<div>ATOM -1:X= 0.85500000 Y=0.85500000 Z=0.85500000<br>
</div>
<div>ATOM -1:X= 0.14500000 Y=0.14500000 Z=0.14500000<br>
</div>
<div>Fe NPT= 781 R0=0.00005000 RMT= 2.0000 Z: 26.000<br>
</div>
<div><br>
</div>
<div>ATOM 2: X=0.94499999 Y=0.55500000 Z=0.25000000<br>
</div>
<div>ATOM 2:X= 0.05500001 Y=0.44500000 Z=0.75000000<br>
</div>
<div>ATOM 2:X= 0.55500000 Y=0.25000000 Z=0.94499999<br>
</div>
<div>ATOM 2:X= 0.44500000 Y=0.75000000 Z=0.05500001<br>
</div>
<div>ATOM 2:X= 0.25000000 Y=0.94499999 Z=0.55500000<br>
</div>
<div>ATOM 2:X= 0.75000000 Y=0.05500001 Z=0.44500000<br>
</div>
<div>O NPT= 781 R0=0.00010000 RMT= 2.0000 Z: 8.000<br>
</div>
<span></span>...............................................</div>
<div>After this one can split Fe, with two Fe 'up' and two 'dn' then 'sgroup' will modify the parameters and the SG=161<br>
</div>
<div>the cell will look different, since one Fe will be moved to 0,0,0 since it does not have inversion symmetry</div>
<div>but you can symmetrize it with</div>
<div><span>****<br>
</span></div>
<div><span>Fe2O3.outputsgroup;<br>
</span></div>
<div><span>.....<br>
</span></div>
<div><span>Note that shift vectors for this space group are defined<br>
</span>
<div>only up to the vector { Z, Z, Z }.<br>
</div>
<span>Here Z can take any value.</span></div>
<div><span>****</span></div>
<div><span>and obtain the cell that I suggested last friday<br>
</span></div>
<div><span><br>
</span></div>
<div><span>Pablo<br>
</span></div>
</span></font></div>
<br>
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