IrrepBZ program on-the-fly generates the irreducible representations (Irreps) of wavevector group, also known as the small representations of little group, at any given points of the Brillouin zone (BZ).
Functionality:
- If the crystal structure is only present either in the POSCAR file (VASP) or scf.in file (Quantum Espresso), the information related to spatial symmetry such as crystal system, holohedral point group, symmetry operations of the space group, and so on, will be documented in the 'IrrepBZ.txt' file.
- besides crystal structure file, if a 'k-points-list' file is also present, which provides the coordinates of the k-points to be investigated, then the small representaions of k-point little groups, under different scenarios, considering the presence or absence of spin-orbit coupling and time-reversal symmetry, will be generated on-the-fly in seperate 'Irrep_ik*.txt' files, one for each k-point.
- besides crystal structure file, if there is a 'qe_band' folder, consisting of 'wfc*.dat' files along with 'data-file-schema.xml' file obtained from the prefix.save folder after performing a nscf calculation with Quantum Espresso, the irreducible representations of electronic bands present in, like, wfc1.dat will be saved to a 'band_ik1.txt' file within the same folder.
- besides crystal structure file, if there is an additional 'qe_phonon' folder, containing 'matdyn.freq' and 'matdyn.eig' files generated through the implementation of matdyn.x in the phonon calculation utilizing Quantum Espresso, the irreducible representations of normal vibrations at specific N-th q-point will be recorded in a 'phonon_iqN.txt' file within the same folder.
- besides crystal structure file, if there is also a 'vasp_band' folder which includes the 'WAVECAR' file obtained from a non-consistent calculation using VASP, the irreducible representations of electronic bands present in the WAVECAR file will be saved in seperate 'band_ik*.txt' files within the same folder, each corresponding to one k-point.
- besides crystal structure file, if there is also a 'vasp_phonon' folder that includes the 'band.yaml' or 'qpoints.yaml' files obtained from a phonon calculation using the Phonopy package interfaced with VASP, the irreducible representations of normal vibrations at specific N-th q-point will be recorded in a 'phonon_iqN.txt' file within the same folder.
Beware:
- Please note that only one crystal structure is processed at a time, so either the POSCAR or scf.in file can exist, but not both simultaneously.
- In the scf.in file, only the tags of ibrav, celldm, nat, and ntyp are allowed to be present in the SYSTEM namelist.
- If the scf.in file exists, it is optional for the 'k-points-list' file, 'qe_band' folder, and 'qe_phonon' folder to exist. They can all exist together, none of them can exist, or they can exist in any combination. The same rule applies to the 'k-points-list' file, 'vasp_band' folder, and 'vasp_phonon' folder in the case of the POSCAR file.
- Regarding the 'vasp_phonon' folder, the q-points can be specified either in a band format or as discrete q-points in the Phonopy implementation. These correspond respectively to the resulting files of 'band.yaml' and 'qpoints.yaml'. Therefore, only one of these files is required and they cannot coexist together.
What is solely needed is a Fortran compiler with default gfortran. No third-party dependency is needed.
Go to the IrrepBZ directory and just type "make", the executable called IrrepBZ will be generated under this directory.
If the source files in src have been modified, first "make clean", then "make"
- Jianqi Huang (Liaoning Academy of Materials, Shenyang 110167, China. Email:jqhuang@lam.ln.cn)