<div dir="ltr">Dear Paolo, <div><br></div><div>Do you mean: "a*sqrt(3)/2" instead of "2a/sqrt(3)", right?</div><div><br></div><div>Otherwise I'm lost... I would understand small numeric deviations from the totally simmetric axes, but "2a/sqrt(3)" means that the correct axes would be those ones:</div><br><div><table border="0" cellpadding="0" cellspacing="0" width="256" style="border-collapse:collapse;width:192pt">
<colgroup><col width="88" style="width:66pt">
<col width="84" span="2" style="width:63pt">
</colgroup><tbody><tr height="19" style="height:14.4pt">
<td height="19" class="" align="right" width="88" style="height:14.4pt;width:66pt">0.852441</td>
<td class="" align="right" width="84" style="width:63pt">0.000000</td>
<td class="" align="right" width="84" style="width:63pt">0.000000</td>
</tr>
<tr height="19" style="height:14.4pt">
<td height="19" class="" align="right" style="height:14.4pt">-0.426221</td>
<td class="" align="right"><b>0.984314</b></td>
<td class="" align="right">0.000000</td>
</tr>
<tr height="19" style="height:14.4pt">
<td height="19" class="" align="right" style="height:14.4pt">0.000000</td>
<td class="" align="right">0.000000</td>
<td class="" align="right">1.000000</td>
</tr></tbody></table></div><div><br></div><div>which are quite far away from mines:</div><br><table border="0" cellpadding="0" cellspacing="0" width="249" style="border-collapse:collapse;width:186pt">
<colgroup><col width="83" span="3" style="width:62pt">
</colgroup><tbody><tr height="19" style="height:14.4pt">
<td height="19" class="" align="right" width="83" style="height:14.4pt;width:62pt">0.852441</td>
<td class="" align="right" width="83" style="width:62pt">0.000000</td>
<td class="" align="right" width="83" style="width:62pt">0.000000</td>
</tr>
<tr height="19" style="height:14.4pt">
<td height="19" class="" align="right" style="height:14.4pt">-0.426221</td>
<td class="" align="right"><b>0.738236</b></td>
<td class="" align="right">0.000000</td>
</tr>
<tr height="19" style="height:14.4pt">
<td height="19" class="" align="right" style="height:14.4pt">0.000000</td>
<td class="" align="right">0.000001</td>
<td class="" align="right">1.000000</td></tr></tbody></table> <br><div>I always calculate the axes this way (triclinic cell's vectors), using my own fortran code (this is probably the error, do I need to fix the number of decimals that appearm right?):</div><div><br></div><div> v1 = (a, 0, 0),<br></div><div> v2 = (b*cos(gamma), b*sin(gamma), 0)</div><div> v3 = (c*cos(beta), c*(cos(alpha)-cos(beta)cos(gamma))/sin(gamma), c*sqrt( 1 + 2*cos(alpha)cos(beta)cos(gamma)- cos(alpha)^2-cos(beta)^2-cos(gamma)^2 )/sin(gamma)</div><div> <br></div><div>And those are the unit cell paramers (extracted from the .cif file that I attach): </div><div><br></div><div><div>_cell_length_a 23.0703</div><div>_cell_length_b 23.0703</div><div>_cell_length_c 27.0638</div><div>_cell_angle_alpha 90.0000</div><div>_cell_angle_beta 90.0000</div><div>_cell_angle_gamma 120.0000</div></div><div><br></div><div>Thanks! For your help and specially for creating this code, I've been working with it quite some time and I'm very satisfied overall. </div><div>Sergi</div><div><br></div></div><div class="gmail_extra"><br><div class="gmail_quote">2015-02-13 14:38 GMT+01:00 Paolo Giannozzi <span dir="ltr"><<a href="mailto:paolo.giannozzi@uniud.it" target="_blank">paolo.giannozzi@uniud.it</a>></span>:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><span class="">On Fri, 2015-02-13 at 11:23 +0100, Sergi Vela wrote:<br>
<br>
> "Error in routine set_sym_bl (1): Symmetry group not a group!<br>
<br>
</span>this is the error<br>
<span class=""><br>
> Use standard orientations for axis"<br>
<br>
</span>and this is a hint. One known case in which this happens is for<br>
hexagonal lattices with a basal crystal axis rotated of 15 degrees<br>
wrt to the cartesian axis.<br>
In your case, it happens (I think) because you choose these axis:<br>
<br>
CELL_PARAMETERS<br>
0.85244126841036916 0.0000000000000000 0.000000<br>
-0.42622032521263958 0.73823597207445180 0.000000<br>
3.13916478650538062E-007 5.43719027573123104E-007 1.000000<br>
<br>
that are very close but not exactly equal to what you wanted:<br>
a 0 0<br>
-a/2 2a/sqrt(3)<br>
0 0 c<br>
so some symmetry operations that should be there, aren't found<br>
<span class=""><br>
> One piece of information: I am running it with QE v.5.1.1. When I run<br>
> it using version 4.2.1 I don't get any error.<br>
<br>
</span>because v.4.2.1 didn't check if the group is a group. It is not needed<br>
in most cases, but for some calculations it is<br>
<br>
Paolo<br>
<span class=""><br>
> Any help is appreciated. Thanks!<br>
><br>
><br>
> Sergi Vela,<br>
> University of Strasbourg<br>
</span>> _______________________________________________<br>
> Pw_forum mailing list<br>
> <a href="mailto:Pw_forum@pwscf.org">Pw_forum@pwscf.org</a><br>
> <a href="http://pwscf.org/mailman/listinfo/pw_forum" target="_blank">http://pwscf.org/mailman/listinfo/pw_forum</a><br>
<br>
<br>
_______________________________________________<br>
Pw_forum mailing list<br>
<a href="mailto:Pw_forum@pwscf.org">Pw_forum@pwscf.org</a><br>
<a href="http://pwscf.org/mailman/listinfo/pw_forum" target="_blank">http://pwscf.org/mailman/listinfo/pw_forum</a><br>
</blockquote></div><br></div>