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Covalent radius

The covalent-radius quantity is aimed at bond-detection and related geometry workflows. It currently ships one preferred target dataset and one legacy support dataset.

Cordero covalent radii (cordero2008)

This is the main covalent-radius target set in the current release line.

  • What it is: a broad covalent-radius compilation based mainly on crystallographic bond distances.
  • Why it matters: it is a modern, widely used reference set for element-wise covalent radii.
  • Coverage: broad coverage across the periodic table, but not complete for every element.
  • How atomref uses it: direct target dataset for covalent-radius lookup.

If you want one covalent set to start with, this is usually the right first choice.

Legacy CSD covalent radii (csd_legacy_cov)

This set reflects the older covalent radii historically used in CSD software for bond perception.

  • What it is: a practical, legacy-oriented bond-assignment table.
  • Why it matters: it has long been used in chemistry software and contains placeholder conventions that are still relevant for compatibility work.
  • Coverage: broad practical coverage, with explicit placeholder values for elements not covered by the historical table.
  • How atomref uses it: support dataset for substitution when the preferred Cordero target set is missing a value.

Because it contains legacy placeholders, it is not the preferred scientific starting point. It is mainly useful as a support layer and for compatibility with older workflows.