findspingroup 0.15.12

FindSpinGroup is a spin space group symmetry analysis toolkit for magnetic materials, first-principles workflows, and high-throughput studies.

FindSpinGroup

FindSpinGroup takes a crystal structure with magnetic moments and identifies:

1. its oriented spin space group (OSSG) in the nonrelativistic limit;
2. the corresponding magnetic space group (MSG) when spin-orbit coupling locks spin and real space; and
3. symmetry constraints on spin splitting, anomalous Hall conductivity, spin texture, polar axes, magnetic sites, and related observables.

Web application: app.findspingroup.com Visualization: view.findspingroup.com SSG Database: database.findspingroup.com

What Can It Tell Me?

Scientific question	Main output	Interpretation
What is the nonrelativistic magnetic symmetry?	OSSG index and symbol	Spin and real-space rotations may act independently.
What symmetry remains with SOC?	MSG BNS number and symbol	Spin rotations are locked to real-space operations.
Are the moments collinear, coplanar, or noncoplanar?	conf	Geometry of the supplied ordered moments; not an FM/AFM label.
Is the configuration FM-like, AFM-like, or altermagnetic?	magnetic_phase	Rule-based classification from symmetry and net moment.
Is spin splitting or AHC allowed?	properties	Allowed/forbidden by symmetry, not a predicted magnitude.
What is the leading spin texture?	spin_texture_config_*	Lowest-order symmetry-allowed momentum polynomial in a documented frame.

Install

pip install --upgrade findspingroup
fsg --version

FindSpinGroup requires Python 3.11 or newer.

Quick Start

Analyze a magnetic CIF, SCIF, or POSCAR input containing magnetic moments (including #MAGMOM= ... in POSCAR):

fsg path/to/structure.mcif

The default output is deliberately short; its core lines are:

FindSpinGroup result
OSSG: 194.164.1.1.L
MSG with SOC: 63.457 Cmcm
Magnetic order: Collinear; AFM(Altermagnet)
Spin splitting: without SOC k-dependent; with SOC allowed
AHC: without SOC forbidden; with SOC forbidden
Leading spin texture: without SOC g-wave; with SOC d-wave

Ask for only the fields you need:

fsg structure.mcif --show index --show magnetic_phase --show msg_bns_number
fsg structure.mcif --show properties
fsg structure.mcif --show spin-texture-no-soc

Use --details for the expanded human-readable symmetry summary, and --json for machine-readable quick-analysis output.

Python: Choose One Main Function

from findspingroup import find_spin_group_basic

summary = find_spin_group_basic("path/to/structure.mcif")

print(summary["index"])
print(summary["magnetic_phase"])
print(summary["msg_bns_number"], summary["msg_symbol"])
print(summary["properties"])

Goal	Python	CLI	Return value
Identify symmetry and screen physical constraints	find_spin_group_basic(...)	fsg FILE	JSON-serializable dictionary
Inspect cells, operations, tensors, sites, or generated artifacts	find_spin_group(...)	fsg --full FILE --show FIELD	MagSymmetryResult
Export operations in the user-supplied cell	find_spin_group_input_ssg(...)	fsg -w FILE	Input-cell operation dictionary

For full analysis, start with the structured accessors instead of the raw attribute dictionary:

from findspingroup import find_spin_group

result = find_spin_group("path/to/structure.mcif")
summary = result.to_summary_dict()       # compact full-route summary
structured = result.to_structured_dict() # groups, cells, properties, artifacts

to_structured_dict() is a semantic Python view and retains operation/domain objects; it is not a directly JSON-serializable contract. Use the basic route or a purpose-built operation export for machine-readable integration.

Supported Inputs

• magnetic CIF / mCIF;
• CIF with supported magnetic-moment tags;
• FindSpinGroup-generated SCIF;
• POSCAR-like files with embedded magnetic moments, or CLI use in a VASP directory with a sibling INCAR containing MAGMOM.

The Python API does not read sibling INCAR files unless explicitly requested; this keeps scripted calls reproducible. See the input guide for the exact behavior.

Documentation

Start with:

• Quickstart
• How to interpret the result
• Choose a workflow or API
• Parameters, tolerances, and reliability
• CLI by task
• Python API

The complete manual is published on Read the Docs. Detailed schemas and diagnostic fields are kept in Reference.

AI agents and tool-using models should start with the dedicated FindSpinGroup AI Agent Guide, which provides a compact route-selection and scientific-interpretation protocol rather than another human tutorial.

How to cite FindSpinGroup

If FindSpinGroup contributes to published work, cite:

Y. Yu, X. Chen, Y. Zhu, Y. Li, R. Xiong, J. Li, Y. Liu, and Q. Liu, "Identifying Oriented Spin Space Groups and Related Physical Properties Using an Online Platform FINDSPINGROUP," arXiv:2604.21397 (2026). https://doi.org/10.48550/arXiv.2604.21397

@article{Yu2026FindSpinGroup,
  title   = {Identifying Oriented Spin Space Groups and Related Physical Properties Using an Online Platform FINDSPINGROUP},
  author  = {Yu, Yutong and Chen, Xiaobing and Zhu, Yanzhou and Li, Yuhui and Xiong, Renzheng and Li, Jiayu and Liu, Yuntian and Liu, Qihang},
  journal = {arXiv preprint arXiv:2604.21397},
  year    = {2026},
  doi     = {10.48550/arXiv.2604.21397},
  url     = {https://arxiv.org/abs/2604.21397}
}

License

Apache License 2.0. See LICENSE.