Dear Malte
This is also a good place for asking, thanks for that.
It is always a good think to check and have a clear idea of how things
are working.
First thing to check the results in the two cases; do they match ?
If this is the case, to understand what is happening you could look at
the symmetries that the program finds in your system; they are always
printed out in the xml file. You should find operations for which t_rev
has a true value, meaning that that operation is usable only together
with the time reversal operation and others, for which has a false
value; these operations do not require the time reversal and only these
will be applied when you do not let the program to use the the t_rev
operation setting no_t_rev to true.
best regards
Pietro
On 09/04/20 09:32, Malte Sachs wrote:
Dear Pietro,
thank you for your answer. I thought if there is no time reversal
symmetry also the combinations with other symmetry operations should
be forbidden. Then it is quite similar to e.g. screw axes with a
combination of rotation+translation although there don't need to be a
rotation present?
My system is orthorhombic. So the twofold axis plus time reversal
leave the spin direction unchanged, right? Question marks started by
comparing QE with the LAPW-code Elk. In the Elk code it seems that
rotation+time-reversal is not used for k-point reduction. However,
this should then be a question for the Elk forum....
Best regards,
Malte
Am 08.04.20 um 16:57 schrieb Pietro Delugas:
Dear Molte
your system could be symmetric under operations made by a rotation +
the time reversal operation, in fact these are the operations that
the no_t_rev option disables, not the time reversal per se.
does the results with and without t_rev compare correctly ?
best regards Pietro
On 08/04/20 12:57, Malte Sachs wrote:
Dear all,
I am performing non-collinear magnetic calculations with spin-orbit
interactions with QE 6.5. As far as I have understand, for a
ferromagnetic system time-reversal symmetry should be broken in this
case.
Although the program detects the right magnetic double point group,
the k-points grid is set up with time-reversal symmetry and I have
to set the no_t_rev flag manually to disable this. Is there any
reason why this isn't done by default (e.g. these calculations can
be done safely with a more reduced k-points grid...)? Do I miss
something?
Best regards,
Malte Sachs
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--
Malte Sachs
Anorganische Chemie, Fluorchemie
Philipps-Universität Marburg
Hans-Meerwein-Straße 4
35032 Marburg (Paketpost: 35043 Marburg)
Tel.: +49 (0)6421 28 - 25 68 0
http://www.uni-marburg.de/fb15/ag-kraus/
_______________________________________________
Quantum ESPRESSO is supported by MaX (www.max-centre.eu/quantum-espresso)
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_______________________________________________
Quantum ESPRESSO is supported by MaX (www.max-centre.eu/quantum-espresso)
users mailing list [email protected]
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