What data do I need?

The checklist

You need	Format	Notes
Structures	CIF text in a cif column of the table, or one <id>.cif file per material in a folder	up to max_sites atoms per cell (default 20); any elements
Properties	one or more numeric columns	any units; each property is standardised unless you say otherwise
An id	a column whose values match the CIF file names (if you use files)	12, 12.0 and "12" are treated as the same id
A family	the prototype your structures share (e.g. cubic ABX₃)	needed for generation; training without one is possible (align_to_prototype: false)

A table like this is enough:

material_id,band_gap,dielectric,cif
mat_001,1.42,18.3,"# generated using pymatgen
data_CsPbBr3
_cell_length_a 5.87 ..."
mat_002,2.16,11.7,"..."

CSV, Excel (.xlsx) and JSON tables are read; Parquet too once pyarrow is installed (pip install "meidnet[parquet]").

How much data?

The published model used 11k structures. A few thousand is typical; a few hundred lets you try the pipeline, but expect rough predictions (the training report tells you how rough).

What happens to each row

meidnet check reads every row exactly as training would and writes check_report.html with one line per reason a row was skipped (unreadable CIF, too many atoms, missing value, does not match the prototype) and example ids. Nothing is silently dropped.

Properties and ranges

MEIDNet can only design for property values it has seen. The check report draws each property's distribution; the generation report flags targets outside the training range as extrapolation.

Which family?

• Cubic ABX₃ perovskite → built-in perovskite_abx3 (variants: oxide, halide, chalcogenide, nitride).
• Rock-salt-ordered double perovskite A₂BB′X₆ → built-in double_perovskite_a2bbx6.
• Anything else with a fixed arrangement of sites → write a family file (positions, which elements may occupy which site, their charges, a cell-size rule, rules).
• Mixed prototypes → you can still train (align_to_prototype: false) and use the model to predict/screen, but generation needs one prototype.