Delocalization effects in singlet fission: Comparing models with two and three interacting molecules

Abstract

Note: This paper is part of the JCP Special Topic on Up-and Down-Conversion in Molecules and Materials.

Simulations of molecular photodynamics in long timescales

“…(a) Parameterized and approximated electronic structure methods Parameterized electronic structure methods speed up quantum chemical (QC) calculations by replacing computationally intensive steps like integral calculations with precomputed quantities either based on empirical [17][18][19] or computational data [20,21]. There are several parameterized electronic structure methods currently available for MQC dynamics, allowing low-cost excited state calculations.…”

“…There are several parameterized electronic structure methods currently available for MQC dynamics, allowing low-cost excited state calculations. Some of them are based on configuration interaction procedures, like FOMO-CI [ 18 ] and OM2/CI [ 17 ]. In turn, TD-DFTB [ 20 ] and the semiempirical TD-SCF [ 3 ] compute excited states based on linear-response time-dependent theory.…”

Excimer formation dynamics in the isolated tetracene dimer

“…[35][36][37] Nonadiabatic dynamics simulations. The nonadiabatic dynamics simulations of the excimer formation process have been performed by employing Tully's surface hopping approach 38 in combination with a modified calculation scheme for the hopping probabilities 39 and using a local diabatisation method to propagate the electronic wavefunction 40,41 . A time step of 0.1 fs was used for the surface hopping simulations.…”

Surface Hopping Dynamics with the Frenkel Exciton Model in a Semiempirical Framework

“…Moreover, no special care is needed to include the superexchange effect, when working in the adiabatic representation. 5 , 26 Computation of the gradient ∇ E K of the adiabatic energies with respect to nuclear coordinates is requested to run SH trajectories. Taking into account that the derivatives of the variationally optimized coefficients C ai , K give a null contribution to the gradient, we have According to the above definitions, the quantities ∇ E gs and ∇ E ai are obtained as algebraic sums of standard QM/MM and MM gradients.…”

“…Probably, the most studied example of the former is the photosynthetic process. 1 − 3 In synthetic systems, EET is relevant in photovoltaic cells, 4 , 5 photochemical switches, 6 , 7 organic optoelectronic devices, 8 etc.…”