Quantum Espresso: Studying topological insulators
       Last update: 2023-10-28
       
       A benchmark density functional theory (DFT) calculation with Quantu
       Espresso has been carried out on NEC SX-Aurora TSUBASA vector compu
       to obtain the electronic properties of bismuth selenide (Bi2Se3)
       topological insulator.
       
 (DOC) 3D Dirac cone of Bi2Se3 (PDF, 1.2 MB)
       
       The raw data (.txt) for reproducing the 3-D linear dispersion relat
       plot can be downloaded below:
       
 (TXT) Bi2Se3 Dirac cone - upper band (TXT, 32 KB)
 (TXT) Bi2Se3 Dirac cone - lower band (TXT, 32 KB)
       
       Calculation details:
       
       + Bi2Se3(111) slab model contained 6 quintuple layers (QL),
         i.e. 30 atomic monolayers,
       
       + Non-collinear calculation with spin-orbit coupling included,
       
       + Grid of 3721 k-points within the first Brillouin zone,
       
       + Ultra-soft pseudopotentials and local density approximation for t
         exchange-correlation functional (LDA),
       
       + Wavefunction and density cut-offs set to 15 and 150 Ry,
         respectively. NOTE: This is a test run. Production calculations
         would require much larger values and proper convergence tests!
       
       + Total energy convergence threshold: 1.0d-6 eV.
       
       Quantum Espresso (version 6.3) has been compiled (vectorised) with 
       compilers (version 3.0.7) and run on 8 vector engines with MPI.
       
       The QE code supporting SX-Aurora TSUBASA architecture:
       https://github.com/SX-Aurora/QuantumEspresso
       
       Performance notes by NEC.
       https://www.nec.com/en/global/solutions/hpc/articles/tech23.html