Internal conversion and intersystem crossing dynamics based on coupled potential energy surfaces with full geometry-dependent spin–orbit and derivative couplings. Nonadiabatic photodissociation dynamics of NH₃(A) leading to the NH(X³Σ⁻, a¹Δ) + H₂ channel

Abstract

We simulate the photodissociation of NH3 originating from its first excited singlet state S1 into the NH2+H (radical) and NH+H2 (molecular) channels. The states considered are the ground singlet state...

Quantum simulation of conical intersections

“…These processes are ubiquitous in nature and have been studied extensively in diverse areas such as spectroscopy, solar energy conversion, chemiluminescence, photosynthesis, and photostability of biomolecules. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] Different potential energy surfaces can intersect at regions that exhibit a conical-shaped topography, known as conical intersections (CIs). [18][19][20][21] In the vicinity of CIs, the Born-Oppenheimer approximation which assumes adiabaticity breaks down.…”

The Unified Hamiltonian Formalism of Spin–Orbit Jahn–Teller and Pseudo-Jahn–Teller Problems in All Axial Symmetries

“…Such SO JT/pJT Hamiltonians are usually resolved using a set of diabatic electronic states − that are significantly mixed along vibrations. Unlike adiabatic states, which are eigenstates of electronic Hamiltonian, diabatic states vary slowly with respect to nuclear distortions, so that the singular nonadiabatic couplings and discontinuous SOC matrix elements , between adiabatic states are avoided, at the cost that the diabatic energies lose the meaning of electronic energy levels. As a consequence of their slow variation, the Hamiltonian matrix elements of those diabatic states are differentiable functions of vibrational coordinates; they can be expanded as Taylor series of those coordinates.…”

Dissociation Time, Quantum Yield, and Dynamic Reaction Pathways in the Thermolysis of trans-3,4-Dimethyl-1,2-dioxetane

“…The enhancement of the quantum yields of singlet and triplet chemiexcitation was achieved experimentally by the methylation of the 1,2-dioxetanes. , The chemiluminescent mechanism has been studied by computing potential energy surface (PESs), locating minima, transition states (TSs), and conical interactions and/or intersystem crossings, and identifying the potential reaction pathways. − The dynamical quantities, e.g., dissociation time and branching ratios, however, cannot be analyzed in the context of critical points and PESs. The high demand for the nonadiabatic molecular dynamics (NAMD) methods, in which the nuclear motion is regulated by multiple electronic states, has led to the development of different approaches. − As the full quantum-mechanical methods are expensive and limited to a few degrees of freedom, − the trajectory surface hopping (TSH) method has emerged as one of the most popular tools for the NAMD simulations, which was used recently to study the chemiluminescent processes for the four-membered heterocyclic peroxides …”