Dear Paulo and Stefano, Thanks for your quick answers! Paulo, of course, you're absolutely right but I already used this property. The comment of Stefano put me on the right track. Initially, I thought that I should not include time-reversal symmetry (TRS) because I have a magnetic system. However, since I did not include SOC, TRS is there. So I added TRS to the list of valid symmetry operations and voilá, I got the same result as QE. Many thanks! :)
Best, Lukas >>> On 02/10/2025 at 03:50 PM, Stefano de Gironcoli <degir...@sissa.it> <degir...@sissa.it> wrote: a symmetry that is always present is k->-k due to time reversal which I think should account for the equivalence between [1/3, 0, 0] and [2/3, 0, 0], up to a G vector as Paolo is mentioning. stefano On 10/02/25 15:11, Paolo Giannozzi wrote: > Not sure I understand the problem: if k is a Bloch vector and G a > reciprocal-lattice vector, k+G is equivalent to k. This property can > be used to reduce the number of inequivalent k-points needed for the > sum over the (irreducible) Brillouin Zone > > Paolo > > On 10/02/2025 14:13, Lukas Cvitkovich wrote: >> >> Non ricevi spesso messaggi di posta elettronica da >> lukas.cvitkov...@physik.uni-regensburg.de. Scopri perché è importante >> <https://aka.ms/LearnAboutSenderIdentification> >> >> >> Dear QE users and developers, >> >> I am currently trying to reproduce the construction of an irreducible >> k- point set as done by QE. >> For this, I set "verbosity = high" to get the symmetry operations >> printed in the output file. >> I start from a uniform k-point mesh. Then, using the same symmetry >> operations as QE, I transform every k-point and fold it back in the >> first Brillouin zone. >> If the resulting k-point falls on another k-point of the uniform >> grid, it is NOT irreducible. >> In this manner, as also described by Blöchl et al (Phys. Rev. B *49*, >> 16223, 1994) I find the set of irreducible kpoints. >> >> My code agrees with QE for a simple structure (fcc crystal tested and >> verified) but I have problems with a more complicated case (the 2D >> magnet FGT). >> In this example, 6 symmetry operations are found (see attached >> QE-output file). >> Starting from a 3x3x3 uniform grid, the irreducible set of kpoints - >> according to QE - contains 7 points. However, I find 12 irreducible >> k- points. >> >> First, please note, that every point found by QE is also contained in >> my set. But I find additional points which (according to QE) should >> be related by some symmetry operation. By looking at the weights, I >> could figure out which kpoints should belong together. >> For instance: According to QE, the kpoints [1/3, 0, 0] and [2/3, 0, >> 0] are equivalent, as well as [0, 0, 1/3] and [0, 0, 2/3] should be >> equivalent too. I recognized that all the extra points could be >> transformed into each other by translating the lattice. However, >> applying all the symmetry operations from the QE output file (these >> are exclusively rotations and not translations), I cannot transform >> these points into each other. You might try for yourself. >> >> So the question that I would like to ask is: Are there any "hidden" >> symmetry operations which are not explicitly printed in the output >> file? Could fractional translations be the reason? Is it maybe >> related to differences between point group and space group? Any other >> hints to what I am missing? >> >> Thank you! Your help would be highly appreciated! >> >> Best, >> Lukas >> >> >> _______________________________________________________________________________ >> >> The Quantum ESPRESSO Foundation stands in solidarity with all >> civilians worldwide who are victims of terrorism, military >> aggression, and indiscriminate warfare. >> -------------------------------------------------------------------------------- >> >> Quantum ESPRESSO is supported by MaX (www.max-centre.eu) >> users mailing list users@lists.quantum-espresso.org >> https://lists.quantum-espresso_______________________________________________________________________________ The Quantum ESPRESSO Foundation stands in solidarity with all civilians worldwide who are victims of terrorism, military aggression, and indiscriminate warfare. -------------------------------------------------------------------------------- Quantum ESPRESSO is supported by MaX (www.max-centre.eu) users mailing list users@lists.quantum-espresso.org https://lists.quantum-espresso.org/mailman/listinfo/users
_______________________________________________________________________________ The Quantum ESPRESSO Foundation stands in solidarity with all civilians worldwide who are victims of terrorism, military aggression, and indiscriminate warfare. -------------------------------------------------------------------------------- Quantum ESPRESSO is supported by MaX (www.max-centre.eu) users mailing list users@lists.quantum-espresso.org https://lists.quantum-espresso.org/mailman/listinfo/users
