The twofold diabatization of the KRb $(1sim 2)^1Pi$ complex in the framework of emph{ab initio} and deperturbation approaches

We performed a diabatization of the mutually perturbed $1^1Pi$ and $2^1Pi$ 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 $1^1Pisim 2^1Pi$ 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.