Workflow

The main command is interactive:

alterseek-path

It proceeds through structure reading, spin-symmetry analysis, path selection, general k-point selection, spin-flip operation selection, and final KPOINTS writing.

Step	What it does	Input needed
0	Finds spin-flip symmetry operations and prints a compact symmetry summary	Structure file; Cartesian spin axis and magnetic moments for non-mcif inputs
1	Builds or reads the high-symmetry IBZ path	Press Enter for auto path, or enter a KPOINTS-style file
2	Chooses the general k point	Automatic IBZ centroid by default
3	Selects the spin-flip operation	Press Enter for default, enter a number, type list, or type manual
4	Builds the altermagnetic path	Automatic
5	Saves the output	Output filename

Step 0: Spin Symmetry

AlterSeeK-Path reads the structure and magnetic moments, then calls findspingroup to identify the altermagnetic phase, report the oriented spin space group index and Chen-Liu symbol, and extract spin-flip and spin-preserving operations.

Supported structure inputs:

• POSCAR
• .vasp
• .cif
• .mcif

For non-magnetic structure formats, enter the collinear spin axis in Cartesian coordinates. The default is 0 0 1, meaning Cartesian z. Then enter scalar moments along that axis in atom order using VASP MAGMOM syntax. For example:

1 -1

or:

5*0 2*1.0

Untyped atoms default to zero moment.

The entered axis is normalized and multiplied by each scalar moment before it is passed to FindSpinGroup. It is a Cartesian spin vector; it is not converted to fractional lattice coordinates. For .mcif files, moments are read directly from the file and this manual-axis prompt is skipped.

For collinear structures, spin-flip operations are identified by the action of each spin-space operation on the collinear spin axis. The written spatial rotation matrices remain in the input-structure basis for use by subsequent path-generation steps.

The structural lattice type determines the Brillouin-zone boundary, the Figure 1 IBZ hull, and HPKOT path. Figures 3 and 4 map that exact Figure 1 hull using FindSpinGroup spin-preserving and spin-flipping operations. If a magnetic state has lower spin symmetry than its structural lattice, these mapped hulls need not fill the whole structural BZ.

Step 1: High-Symmetry K-Path

Press Enter to use the automatically detected SeeK-path.

Alternatively, provide a line-mode KPATH.in or KPOINTS-style file if you want to start from a custom path.

The detected lattice type is reported using SeeK-path lattice keys such as hP2, oI3, or mC2.

Step 2: General K Point

By default, AlterSeeK-Path uses the centroid of the irreducible Brillouin zone as the general k point.

This point is inserted into the high-symmetry path so the band calculation samples spin splitting away from special symmetry lines.

Step 3: Spin-Flip Operation

The workflow lists available spin-flip operations and chooses a default when possible.

You can accept the default, list the available matrices, select another operation, or enter a manual transformation.

Step 4: Build The Altermagnetic Path

The selected operation maps k to k'. AlterSeeK-Path then inserts k and k' into the path so paired spin-splitting segments are sampled systematically.

Internally, the path construction uses the standardized SeeK-path primitive reciprocal basis. At output time, the written KPOINTS coordinates are converted into the reciprocal basis of the input structure used by VASP.

Step 5: Save Outputs

The default output file is:

KPOINTS_modified

The workflow also updates:

alterband.toml

This file records band-plot settings, including the detected lattice type when available.

Depending on the plotting settings, the workflow may also save Brillouin-zone and spin-BZ figures.

Output Files

File	Description
KPOINTS_modified	Altermagnetic k-path for VASP line-mode band calculations
alterband.toml	Band-plot configuration written by the main workflow
spin_operations.txt	Full spin-symmetry operation log
spin_flip_operations.txt	Spin-flip rotation matrices used by the main workflow
spin_preserve_operations.txt	Spin-preserving rotation matrices used for completion and diagnostics
*_ibz_*.png	IBZ/BZ figure with the selected general k point
*_spinflip_*.png	Spin-up/spin-down IBZ connection figure
*_spinbz_*.png	Spin-colored BZ figure
*_spinbz_top_*.png	Top-view spin-colored BZ figure

For Laue groups -1, -3, and m-3, no altermagnetic splitting is supported. The workflow prints a note and writes the ordinary default path.

Next Step

After running the VASP band calculation, see Plotting for spin-resolved band-plot generation.