1. Peak position tolerance: Typically ±5 cm⁻¹ for dispersive IR, ±2 cm⁻¹ for FTIR. But specific bands might have different acceptable ranges based on their nature.

2. Correlation coefficient: Software-based comparisons might require a high similarity score (e.g., ≥0.95).

3. Presence of all major peaks and their relative intensities should match.

4. Consideration of sample preparation methods and instrument type.

Maybe this preprint could be of help: Preprint Exploring Correlation in Infrared Spectroscopy