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

We performed a diabatization of the mutually perturbed $1^1Π$ and $2^1Π$ 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 $\langle ψ_1^{ad}|\partial /\partial R|ψ_2^{ad}\rangle$ 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 $1^1Π\sim 2^1Π$ 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.