{
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "$id": "https://download.lammps.org/json/force-style-test-schema.json",
    "title": "JSON schema for LAMMPS force-style regression test reference files (unittest/force-styles)",
    "description": "Version 0.2; last updated 2026-07-09",
    "type": "object",
    "additionalProperties": false,
    "properties": {
        "lammps_version": {
            "type": "string",
            "description": "LAMMPS version used to last update the reference data"
        },
        "date_generated": {
            "type": "string",
            "description": "date when the file was last updated"
        },
        "epsilon": {
            "type": "number",
            "exclusiveMinimum": 0,
            "description": "base value for the relative precision required for tests to pass"
        },
        "skip_tests": {
            "type": ["string", "null"],
            "description": "space separated list of test fixtures to skip"
        },
        "tags": {
            "type": ["string", "null"],
            "description": "space separated list of tags classifying the test or adjusting fixture behavior"
        },
        "prerequisites": {
            "type": "string",
            "description": "list of style kind / style name pairs required to run the test"
        },
        "pre_commands": {
            "type": ["string", "null"],
            "description": "LAMMPS commands to be executed before the input template file is read (empty allowed)"
        },
        "post_commands": {
            "type": ["string", "null"],
            "description": "LAMMPS commands to be executed right before the actual tests (empty allowed)"
        },
        "input_file": {
            "type": "string",
            "description": "name of the LAMMPS input file template"
        },
        "input_coeffs": {
            "type": "string",
            "description": "name of the file with the force-field/group setup commands (test_fix_timestep only)"
        },
        "natoms": {
            "type": "integer",
            "minimum": 0,
            "description": "number of atoms in the input file template"
        },
        "timestep": {
            "type": "number",
            "exclusiveMinimum": 0,
            "description": "timestep size applied for the test run (when different from the tester default)"
        },
        "pair_style": {
            "type": "string",
            "description": "arguments to the pair_style command to be tested"
        },
        "pair_coeff": {
            "type": "string",
            "description": "list of pair_coeff arguments to set parameters for the input template"
        },
        "init_vdwl": {
            "type": "number",
            "description": "non-Coulomb pair energy after \"run 0\""
        },
        "init_coul": {
            "type": "number",
            "description": "Coulomb pair energy after \"run 0\""
        },
        "run_vdwl": {
            "type": "number",
            "description": "non-Coulomb pair energy after \"run 4\""
        },
        "run_coul": {
            "type": "number",
            "description": "Coulomb pair energy after \"run 4\""
        },
        "bond_style": {
            "type": "string",
            "description": "arguments to the bond_style command to be tested"
        },
        "bond_coeff": {
            "type": "string",
            "description": "list of bond_coeff arguments to set parameters"
        },
        "angle_style": {
            "type": "string",
            "description": "arguments to the angle_style command to be tested"
        },
        "angle_coeff": {
            "type": "string",
            "description": "list of angle_coeff arguments to set parameters"
        },
        "dihedral_style": {
            "type": "string",
            "description": "arguments to the dihedral_style command to be tested"
        },
        "dihedral_coeff": {
            "type": "string",
            "description": "list of dihedral_coeff arguments to set parameters"
        },
        "improper_style": {
            "type": "string",
            "description": "arguments to the improper_style command to be tested"
        },
        "improper_coeff": {
            "type": "string",
            "description": "list of improper_coeff arguments to set parameters"
        },
        "equilibrium": {
            "type": "string",
            "description": "equilibrium distance (bond) or angle (angle) for each type"
        },
        "init_energy": {
            "type": "number",
            "description": "bonded interaction energy after \"run 0\""
        },
        "run_energy": {
            "type": "number",
            "description": "bonded interaction energy after \"run 4\""
        },
        "extract": {
            "type": ["string", "null"],
            "description": "list of keywords supported by the style's extract() method and their dimension (empty allowed)"
        },
        "init_stress": {
            "type": "string",
            "description": "stress tensor after \"run 0\""
        },
        "init_forces": {
            "type": "string",
            "description": "forces on atoms after \"run 0\""
        },
        "run_stress": {
            "type": "string",
            "description": "stress tensor after the run"
        },
        "run_forces": {
            "type": "string",
            "description": "forces on atoms after \"run 4\""
        },
        "run_pos": {
            "type": "string",
            "description": "per-atom positions after the run"
        },
        "run_vel": {
            "type": "string",
            "description": "per-atom velocities after the run"
        },
        "run_torque": {
            "type": "string",
            "description": "per-atom torques after the run, where applicable"
        },
        "init_mag_forces": {
            "type": "string",
            "description": "per-atom magnetic precession vectors after \"run 0\" (atom style spin)"
        },
        "run_mag_forces": {
            "type": "string",
            "description": "per-atom magnetic precession vectors after the run (atom style spin)"
        },
        "run_spin": {
            "type": "string",
            "description": "per-atom spin orientations and magnitudes after the run (atom style spin)"
        },
        "global_scalar": {
            "type": "number",
            "description": "the global scalar output of the tested fix, if any"
        },
        "global_vector": {
            "type": "string",
            "description": "the global vector output of the tested fix, if any"
        },
        "global_array": {
            "type": "string",
            "description": "the global array output of the tested compute or fix (test_output_style)"
        },
        "peratom_data": {
            "type": "string",
            "description": "the per-atom vector or array output of the tested compute or fix (test_output_style)"
        },
        "local_data": {
            "type": "string",
            "description": "the local vector or array output of the tested compute or fix (test_output_style)"
        }
    },
    "required": [
        "lammps_version",
        "date_generated",
        "epsilon",
        "prerequisites",
        "pre_commands",
        "post_commands",
        "input_file",
        "natoms"
    ],
    "oneOf": [
        {
            "title": "test_pair_style reference",
            "required": [
                "pair_style",
                "pair_coeff",
                "init_vdwl",
                "init_coul",
                "run_vdwl",
                "run_coul",
                "extract",
                "init_stress",
                "init_forces",
                "run_stress",
                "run_forces"
            ]
        },
        {
            "title": "test_bond_style reference",
            "required": [
                "bond_style",
                "bond_coeff",
                "equilibrium",
                "init_energy",
                "run_energy",
                "extract",
                "init_stress",
                "init_forces",
                "run_stress",
                "run_forces"
            ]
        },
        {
            "title": "test_angle_style reference",
            "required": [
                "angle_style",
                "angle_coeff",
                "equilibrium",
                "init_energy",
                "run_energy",
                "extract",
                "init_stress",
                "init_forces",
                "run_stress",
                "run_forces"
            ]
        },
        {
            "title": "test_dihedral_style reference",
            "required": [
                "dihedral_style",
                "dihedral_coeff",
                "init_energy",
                "run_energy",
                "extract",
                "init_stress",
                "init_forces",
                "run_stress",
                "run_forces"
            ]
        },
        {
            "title": "test_improper_style reference",
            "required": [
                "improper_style",
                "improper_coeff",
                "init_energy",
                "run_energy",
                "extract",
                "init_stress",
                "init_forces",
                "run_stress",
                "run_forces"
            ]
        },
        {
            "title": "test_fix_timestep reference",
            "required": [
                "run_pos",
                "run_vel"
            ]
        },
        {
            "title": "test_min_style reference",
            "required": [
                "input_coeffs",
                "init_energy",
                "run_energy",
                "global_scalar",
                "global_vector"
            ],
            "not": {
                "required": ["run_pos"]
            }
        },
        {
            "title": "test_output_style reference",
            "required": [
                "timestep"
            ],
            "anyOf": [
                { "required": ["global_scalar"] },
                { "required": ["global_vector"] },
                { "required": ["global_array"] },
                { "required": ["peratom_data"] },
                { "required": ["local_data"] }
            ],
            "not": {
                "anyOf": [
                    { "required": ["run_pos"] },
                    { "required": ["init_energy"] }
                ]
            }
        }
    ]
}