TB2J_edit

TB2J_edit is a tool for modifying TB2J results. It allows you to post-process the exchange parameters calculated by TB2J, such as adding single-ion anisotropy, toggling DMI or anisotropic exchange, and symmetrizing the exchange parameters.

Command Line Interface

The TB2J_edit.py command provides several subcommands:

Load and Save

Simply load and save the results (useful for format conversion or checking if the file is valid).

TB2J_edit.py load -i TB2J_results/TB2J.pickle -o modified_results

Set Single-Ion Anisotropy

Set the single-ion anisotropy (SIA) for specific atomic species.

# Set Sm anisotropy to 5 meV along z-axis
TB2J_edit.py set-anisotropy -i TB2J_results/TB2J.pickle -o modified_results -s Sm 5.0 -d "0 0 1" -m

  • -s SPECIES K1: Set the anisotropy constant K1 for SPECIES. Can be used multiple times.

  • -d "x y z": Set the direction of the anisotropy axis (default is [0, 0, 1]).

  • -m: Interpret K1 in meV (default is eV).

Toggle DMI and Anisotropic Exchange

Enable or disable Dzyaloshinskii-Moriya Interaction (DMI) or anisotropic exchange (Jani).

# Disable DMI
TB2J_edit.py toggle-dmi -i TB2J_results/TB2J.pickle -o modified_results --disable

# Enable Anisotropic Exchange
TB2J_edit.py toggle-jani -i TB2J_results/TB2J.pickle -o modified_results --enable

# Disable Isotropic Exchange
TB2J_edit.py toggle-exchange -i TB2J_results/TB2J.pickle -o modified_results --disable

Symmetrize Exchange

Symmetrize the isotropic exchange parameters based on a reference crystal structure. This is useful if the calculated J values slightly break symmetry due to numerical noise or if you want to enforce a higher symmetry (e.g., from a high-temperature phase).

TB2J_edit.py symmetrize -i TB2J_results/TB2J.pickle -S structure.cif -o modified_results

  • -S STRUCTURE: Path to the reference structure file (e.g., CIF, POSCAR).

Remove Sublattice

Remove all magnetic interactions associated with a specific sublattice. This includes Single-Ion Anisotropy (SIA), Exchange (J), DMI, and Anisotropic Exchange involving atoms of the specified species.

TB2J_edit.py remove-sublattice -i TB2J_results/TB2J.pickle -o modified_results -s Sm

  • -s SUBLATTICE: The name of the sublattice (species symbol) to remove (e.g., ‘Sm’, ‘Fe’).

Info

Show information about the TB2J results, including composition, number of magnetic atoms, and enabled interactions.

TB2J_edit.py info -i TB2J_results/TB2J.pickle

Python API

You can also use the TB2J.io_exchange.edit module in your Python scripts.

from TB2J.io_exchange.edit import load, set_anisotropy, set_sia_tensor, remove_sia_tensor, toggle_DMI, toggle_exchange, save

# Load results
spinio = load('TB2J_results/TB2J.pickle')

# Modify results
set_anisotropy(spinio, species='Sm', k1=5.0, k1dir=[0, 0, 1]) # k1 in eV

# Set full 3x3 SIA tensor
import numpy as np
tensor = np.diag([0.001, 0.002, 0.003]) # eV
set_sia_tensor(spinio, species='Sm', tensor=tensor)

toggle_DMI(spinio, enabled=False)
toggle_exchange(spinio, enabled=False)

# Save results
save(spinio, 'modified_results')

Functions

  • load(path): Load TB2J results from a pickle file.

  • save(spinio, path): Save modified results to a directory.

  • set_anisotropy(spinio, species, k1, k1dir): Set uniaxial single-ion anisotropy.

  • set_sia_tensor(spinio, species, tensor): Set full single-ion anisotropy tensor.

  • remove_sia_tensor(spinio, species): Remove single-ion anisotropy tensor.

  • toggle_DMI(spinio, enabled): Enable/disable DMI.

  • toggle_Jani(spinio, enabled): Enable/disable anisotropic exchange.

  • toggle_exchange(spinio, enabled): Enable/disable isotropic exchange.

  • remove_sublattice(spinio, sublattice_name): Remove interactions for a sublattice.

  • symmetrize_exchange(spinio, atoms, symprec): Symmetrize exchange parameters.