  We performed a diabatization of the mutually perturbed $1^1\Pi$ and $2^1\Pi$
states of KRb based on both electronic structure calculation and direct
coupled-channel deperturbation analysis of experimental energies. The potential
energy curves (PECs) of the diabatic states and their scalar coupling were
constructed from the \textit{ab initio} adiabatic PECs by analytically
integrating the radial $\langle \psi_1^{ad}|\partial /\partial
R|\psi_2^{ad}\rangle$ matrix element obtained by a finite-difference method.
The diabatic potentials and electronic coupling function were refined by the
least squares fitting of the rovibronic termvalues of the $1^1\Pi\sim 2^1\Pi$
complex. The empirical PECs combined with the coupling function as well as the
diabatized spin-orbit coupling and transition dipole matrix elements are useful
for further deperturbation treatment of both singlet and triplet states
manifold.
