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

TL;DR

This study presents a combined b initiond deperturbation approach to accurately diabatize the perturbed $1^1\u03a0$ and $2^1\u03a0$ states of KRb, providing refined potential energy curves and coupling functions for future spectroscopic analysis.

Contribution

It introduces a novel combined b initiond empirical method for diabatization of the KRb $1^1\u03a0$ and $2^1\u03a0$ states, enhancing the accuracy of potential energy and coupling models.

Findings

Constructed diabatic potential energy curves and coupling functions.

Refined empirical PECs through least squares fitting.

Provided useful data for further deperturbation analysis.

Abstract

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.