fix: [Phase 3] Implement Intrinsic Bond Order (IBO)

pymultiwfn/bonding/bonding.py

@@ -10,6 +10,7 @@
 
 from ..io import load
 from .fuzzy import FuzzyAtom, fuzzy_bond_order, calculate_fuzzy_bond_order_matrix
+from .intrinsic import intrinsic_bond_order, calculate_intrinsic_bond_order_matrix, IntrinsicBondResult
 
 
 class Bonding:
@@ -114,3 +115,38 @@ def get_fuzzy_bond_order_matrix(self) -> np.ndarray:
                 self.fuzzy_atoms
             )
         return self._fuzzy_matrix
+
+    def get_intrinsic_bond_order(self, atom_i: int, atom_j: int) -> float:
+        """Calculate intrinsic bond order between two atoms.
+
+        The intrinsic bond order (IBO) accounts for bond polarity
+        and provides a measure of the intrinsic covalent character
+        of a bond.
+
+        Args:
+            atom_i: Index of first atom (0-based)
+            atom_j: Index of second atom (0-based)
+
+        Returns:
+            Intrinsic bond order value
+
+        Raises:
+            ValueError: If atom indices are invalid
+        """
+        if not (0 <= atom_i < self.natoms and 0 <= atom_j < self.natoms):
+            raise ValueError(f"Atom indices must be in range [0, {self.natoms})")
+        if atom_i == atom_j:
+            raise ValueError("Atom indices must be different")
+
+        return intrinsic_bond_order(self.wfn, atom_i, atom_j)
+
+    def get_intrinsic_bond_order_matrix(self) -> IntrinsicBondResult:
+        """Calculate intrinsic bond order matrix for all atom pairs.
+
+        Returns:
+            IntrinsicBondResult containing:
+            - bond_order_matrix: NxN matrix of intrinsic bond orders
+            - polarity_matrix: NxN matrix of bond polarity corrections
+            - wiberg_matrix: NxN matrix of Wiberg bond orders
+        """
+        return calculate_intrinsic_bond_order_matrix(self.wfn)