{
  "convergence_variable": {
    "description": "Plane wave energy cutoff",
    "parameter": "ENCUT",
    "unit": "eV",
    "values": [
      280,
      300,
      320,
      340,
      360
    ]
  },
  "description": "For a fixed structure (Al face-centered cubic), run 5 single-point energy calculations with varying ENCUT (280, 300, 320, 340, 360 eV). All other parameters must be strictly constant: k-point mesh, ISMEAR, SIGMA, POTCAR path, etc. This verifies systematic parameter scanning ability.",
  "expected_output": {
    "analysis": "plot energy vs ENCUT to show convergence curve",
    "format": "5 OUTCAR files or energy log",
    "naming": "Al_ENCUT_{energy_ev}_eV_energy.txt or similar"
  },
  "locked_parameters": {
    "ALGO": "Fast",
    "IBRION": -1,
    "ISMEAR": 1,
    "NSW": 0,
    "POTCAR": "PAW_PBE/Al/POTCAR",
    "SIGMA": 0.1,
    "k_point_mesh": "8 8 8"
  },
  "structure": {
    "crystal_system": "cubic",
    "formula": "Al",
    "lattice_constant_A": 4.05,
    "space_group": "Fm-3m"
  },
  "task": "batch_convergence_test_ENCUT_sweep",
  "verification_checklist": [
    "Parameter ENCUT varies from 280→360 eV",
    "All 5 calculations use identical k-point mesh 8x8x8",
    "ISMEAR, SIGMA unchanged across runs",
    "Output file sequence shows clear parameter progression",
    "Can extract energies and produce convergence plot"
  ]
}