Ab initio functional-independent calculations of the clamped Pockels tensor of tetragonal barium titanate

Pockels calculation implementation in aiida-vibroscopy

The Pockels calculation capability was implemented in the aiida-vibroscopy src/aiida_vibroscopy/data/vibro_mixin.py code and released under version v1.2.0.

Which codes versions were used

The calculations can be performed and reproduced with the following AiiDA plugins and codes:

How to navigate through the archive

The "aiida" data is reported as an AiiDA database and can be accessed either on-line through the Rest-API capability of the Materials Cloud, or by importing the data in an AiiDA installation. The "hubbard" data is reported as Quantum Espresso input/output files and can be read directly in a notebook or a terminal.

The "aiida" repository contains 10 production nodes identified with their respective UUID's (a universal identifier referring to a specific node in the database). The first 7 production nodes are IRamanSpectraWorkChain whose outputs (i.e. data structures labelled as VibrationalData) include the

  • Pockels tensor
  • Dielectric tensor
  • Born effective charges
  • Raman tensors
  • Non-linear optical susceptibility tensor ($\chi^{(2)}$)
  • Force constants
  • Unit cell
  • Primitive matrix (which defines the primitive cell)
  • Supercell matrix (supercell relative to the force constants)
  • Atomic species and positions for BaTiO3 P4bm StructureData with different titanium displacements: uuid 7c7a6488-eccf-40e3-887e-20b8d12d1c14: 0.425% uuid 65a0e63c-525f-40aa-8873-de12dc7c4447: 0.450% uuid 53bdca94-c60a-4674-be4b-c50f23892767: 0.466% uuid 59252e4c-1823-4bee-bf2d-0df87d7c30f6: 0.500% uuid 7b12410c-43a4-4a82-a76d-e399af585a0a: 0.533% uuid 3bbe2887-2fac-458b-b320-988a9f5ec703: 0.566% uuid 1de97094-2708-4b2d-a988-ef4a4057ece4: 0.600%

The next production node, with uuid b6e7dd49-1074-45a2-9a29-0b5d8d61cffe, is a IRamanSpectraWorkChain node computing the Pockels tensor and aforementioned data structures of BaTiO3 HubbardStructureData with U and V Hubbard parameters.

The last two production nodes are HarmonicWorkChain nodes computing the band structure of BaTiO3 with space groups

  • P4mm (uuid a83b0c05-1d40-4bd7-a3ac-807f009ec885) and
  • P4bm (uuid eb0d9f19-2ade-483c-9085-3fe287dcc8d3).

The "hubbard" repository contains Hubb_card.in and hp.in input files. The former is to be run with the pw.x Quantum Espresso executable, whereas the latter is to be run with hp.x. The result of hp.x provides us with the U and V pairs and parameters for P4bm BaTiO3 in the HUBBARD.dat file. These parameters are imported into the aiida database in order to run the IRamanSpectraWorkChain production node with uuid b6e7dd49-1074-45a2-9a29-0b5d8d61cffe.