Mind the GAP: quantifying the breakdown of the linear vibronic coupling Hamiltonian

Abstract

Excited state dynamics play a critical role across a broad range of scientific fields. Importantly, the highly non-equilibrium nature of the states generated by photoexcitation means that excited state simulations...

Spin-Vibronic Intersystem Crossing and Molecular Packing Effects in Heavy Atom Free Organic Phosphor

“…A GAP of around 10% suggests that anharmonicity effects are small and the LVC potential can be considered a reliable approximation. While the T 1 state slightly exceeds this value, we note that the majority of this is due to the effect of the JT coupling, which gives rise to a gradient at the FC geometry in the state energies and inflates the GAP . In addition, the geometries predicted by the LVC model are very similar to the fully optimized structures, with the RMSD of the T 1 state being 0.007 Å.…”

“…The validity of the linear vibronic coupling Hamiltonian in this case is based upon the assumption that the rigidity of HTANGO means that anharmonicity of the potential energy surfaces does not play a significant role in the dynamics. To assess the accuracy, we use the recently introduced Global Anharmonicity Parameter 77 (GAP), which in the S 1 state is 5% and in the T 1 state is 13%. A GAP of around 10% suggests that anharmonicity effects are small and the LVC potential can be considered a reliable approximation.…”

“…Intrastate coupling terms are derived from the Franck–Condon (FC) geometry using the method outlined by Eng et al 77 The JT terms were calculated in the same way, using the gradient of the adiabatic state at the FC geometry.…”

Using non-adiabatic excitation transfer for signal transmission between molecular logic gates

“…If the system meets these requirements, a PES can be calculated only from equilibrium coordinates and a Hessian. According to this, Penfold and Eng [39] developed a method for controlling that a transition meets the requirements of the Franck-Condon (FC) approximation. One needs to know the exact gradient elements κ j of the final state which can be calculated ab initio, and the gradient elements κ * j within harmonic approximation which can be evaluated via the formula…”

A review of fused-ring carbazole derivatives as emitter and/or host materials in organic light emitting diode (OLED) applications

“…137 In the ground state geometry all the A units are tilted by 57° with respect to the TAT core. 138 After excitation the A units can rotate around the C-N bonds to minimise the orbital overlap. Calculations showed ten possible conformers of TAT-3DBTO 2 all within 0.03 eV of each other, and Δ E ST 0.01 eV was obtained from PL studies, with k RISC as fast as 1 × 10 7 s −1 and PLQY ≈ 1, doped in BCPO film.…”