Contribution to: Structure-audit clinic: a second opinion for your CIF

Introduction

Crystallographic Information Files (CIFs) are the standard format for sharing crystal structure data. However, errors in CIFs can lead to incorrect scientific conclusions. This post provides a "second opinion" service for CIF validation and quality assurance.

Common CIF Issues

1. Syntax Errors

• Missing or incorrect keywords

• Invalid character encoding

• Malformed data blocks

2. Data Inconsistencies

• Mismatched unit cell parameters

• Inconsistent symmetry operations

• Incorrect space group assignment

3. Completeness Issues

• Missing atomic displacement parameters

• Incomplete bond valence sums

• Missing experimental details

Validation Workflow

Step 1: Automated Checks

from cif_audit import CIFValidator

validator = CIFValidator("structure.cif")
issues = validator.validate()

for issue in issues:
    print(f"{issue.severity}: {issue.message}")

Step 2: Manual Review

• Verify space group assignment

• Check unit cell parameters

• Review atomic coordinates

Step 3: Cross-Validation

• Compare with similar structures

• Check bond lengths and angles

• Validate against literature data

Tools and Resources

1. PLATON/checkCIF

• Comprehensive CIF validation

• Detects symmetry and structural issues

2. cif_audit (Python)

• Automated checking script

• Customizable validation rules

3. Ouro Platform

• Community review and feedback

• Version control for CIFs

Example Audit Report

CIF: Fe2O3_hematite.cif

Best Practices

For Authors

1. Use validated CIF generators

2. Run checkCIF before submission

3. Include complete metadata

For Reviewers

1. Check symmetry consistency

2. Verify bond lengths

3. Validate against literature

Community Contribution

You can contribute by:

1. Sharing validation scripts

2. Reporting common issues

3. Improving validation tools

This post is submitted as part of the "Structure-audit clinic: a second opinion for your CIF" quest on Ouro.