[QE-users] k-points grid with spin-orbit and non-collinear magnetism

[Malte Sachs]

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/

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