kappa1_index#

skfp.descriptors.kappa1_index(mol: Mol) → float#

First Kappa shape index (K1).

Computes the first kappa shape index [1], which measures molecular shape based on single bonds. It is given by the equation:

\[K_1 = \frac{(A + \alpha) (A + \alpha - 1)^2}{P_1^2}\]

where:

  • A is the number of heavy atoms

  • α is the Hall-Kier alpha index

  • P1 is the number of single bonds

This index provides insight into the molecular shape and branching properties.

Parameters:

mol (RDKit Mol object) – The molecule for which the first Kappa shape index is calculated.

References

Examples

>>> from rdkit.Chem import MolFromSmiles
>>> from skfp.descriptors import kappa1_index
>>> mol = MolFromSmiles("C1=CC=CC=C1")  # Benzene
>>> kappa1_index(mol)
3.4115708812260532
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