Nonadiabatic coupling and diabatic electronic population dynamics on 1¹A₂ and 1¹B₁ states of ozone molecule

Abstract

In this work, we examine nonadiabatic population dynamics for 1 1 B 1 and 1 1 A 2 states of ozone molecule (O 3 ). In O 3 , two lowest singlet excited states, 1 A 2 and 1 B 1 , can be coupled. Thus, population transfer between them occurs through the seam involving these two states. At any point of the seam (conical intersection), the Born-Oppenheimer approximation breaks down, and it is necessary to investigate nonadiabatic dynamics. We consider a linear vibronic coupling Hamiltonian model and evaluate vibronic coupling constant, diabatic frequencies for three modes of O 3 , bilinear and quadratic coupling constants for diabatic potentials, displacements, and Huang-Rhys coupling constants using ab initio calculations. The electronic structure calculations have been performed at the multireference configuration interaction and complete active space with second-order perturbation theory with a full-valence complete active space self-consistent field methods and augmented Dunning's standard correlation-consistent-polarized quadruple zeta basis set to determine ab initio potential energy surfaces for the ground state and first two excited states of O 3 , respectively. We have chosen active space comprising 18 electrons distributed over 12 active orbitals. Our calculations predict the linear vibronic coupling constant 0.123 eV. We have obtained the population on the 1 1 B 1 and 1 1 A 2 excited electronic states for the first 500 fs after photoexcitation.

Investigation of nonadiabatic coupling and diabatic electronic population dynamics on F2O+ cation within multi reference configuration interaction calculations

“…To obtain the accurate equilibrium geometries and harmonic vibrational frequencies, the augmented Dunning's standard correlation consistent polarized valence Q zeta basis set (Aug‐cc‐pVQZ) at the ab initio CASSCF level with full‐valence complete active space was chosen on the basis of our previous work on ozone molecule [31]. Equilibrium geometries and harmonic vibrational frequencies have been obtained for the ground ( 2 B 1 ), first excited ( 2 A 1 ) and second excited ( 2 B 2 ) electronic states at CASSCF/Aug‐cc‐pVQZ level of theory.…”

“…Generally, when two electronic states approach each other and the CI between them occurs, the behavior of nuclear dynamics can be simplified by converting adiabatic to diabatic representation [30]. In adiabatic representation, the vibronic coupling between states is represented by off‐diagonal elements of the kinetic energy matrix and the potential energy matrix remains in diameter, but in diabatic representation the diagonal elements are the PESs for population acceptor and donor states E a ( Q ) and E d ( Q ), respectively, and vibronic coupling between states represented by the off‐diagonal elements of the potential energy matrix (Λ ad ( Q ) = Λ da ( Q )) that are uniform functions of nuclear coordinates [31].…”

“…The vibronic coupling parameters of F 2 O + including vibronic coupling constant of the anti‐symmetric stretching mode, linear coupling constants of the two totally symmetric modes (bending and symmetric stretching modes, ω 1 , ω 2 , respectively) with a 1 symmetry and also bilinear coupling constants have been obtained using the same methodology in our previous reports [26, 31]. In F 2 O + molecule, according to symmetry selection rule [33], the anti‐symmetric stretching mode is responsible for the vibronic coupling between 2 B 2 and 2 A 1 excited electronic sates.…”

“…Detailed description on derivation of a general mathematical statement including the displacements, and distortions of PESs, for the electronic populations dynamics between two diabatic electronic states using nonequilibrium Fermi golden rule can be found in our previous works [26, 31].…”