pauli matrices in yambo

Various technical topics such as parallelism and efficiency, netCDF problems, the Yambo code structure itself, are posted here.

Moderators: Davide Sangalli, andrea.ferretti, myrta gruning, andrea marini, Daniele Varsano, Conor Hogan, Nicola Spallanzani

Post Reply
batman
Posts: 12
Joined: Sun Jun 20, 2021 2:04 pm

pauli matrices in yambo

Post by batman » Mon Jun 26, 2023 3:36 pm

Dear Developers,

The sigma_y matrix defined in "yambo/src/modules/mod_D_lattice.F" is not correct. As Fortran in column major, reshaping [1,2,3,4] will give ([[1 3],[2 4]])
so the matrix is currently defined as -sigma_y(actual). I can see that in one of the Tait-Bryan angles (beta) defined in "yambo/src/setup/build_spin_sop.F" lacks minus sign. I guess the minus was removed to compensate this. When rotating spinors wave functions with time reversal symmetry, it picks up an additional phase of -1 (which does not effect the results due to gauge arbitrary ness). I also see some other instances where sigma_y is used. Is it a bug or was it intentionally coded in this way?

Best regards,
Murali
Muralidhar Nalabothula
Doctoral student at Department of Physics and Materials Science,
Université du Luxembourg

User avatar
Davide Sangalli
Posts: 617
Joined: Tue May 29, 2012 4:49 pm
Location: Via Salaria Km 29.3, CP 10, 00016, Monterotondo Stazione, Italy
Contact:

Re: pauli matrices in yambo

Post by Davide Sangalli » Mon Jun 26, 2023 3:46 pm

I opened an issue: https://github.com/yambo-code/yambo/issues/50
Better to double check this.
I do not think it was coded like that on purpose.

Best,
D.
Davide Sangalli, PhD
CNR-ISM, Division of Ultrafast Processes in Materials (FLASHit) and MaX Centre
https://sites.google.com/view/davidesangalli
http://www.max-centre.eu/

Post Reply