Quantum dynamics simulation of intramolecular singlet fission in covalently linked tetracene dimer

Abstract

In this work, we study singlet fission in tetracene para-dimers, covalently linked by a phenyl group. In contrast to most previous studies, we account for the full quantum dynamics of the combined excitonic and vibrational system. For our simulations, we choose a numerically unbiased representation of the molecule’s wave function, enabling us to compare with experiments, exhibiting good agreement. Having access to the full wave function allows us to study in detail the post-quench dynamics of the excitons. Here, one of our main findings is the identification of a time scale t0 ≈ 35 fs dominated by coherent dynamics. It is within this time scale that the larger fraction of the singlet fission yield is generated. We also report on a reduced number of phononic modes that play a crucial role in the energy transfer between excitonic and vibrational systems. Notably, the oscillation frequency of these modes coincides with the observed electronic coherence time t0. We extend our investigations by also studying the dependency of the dynamics on the excitonic energy levels that, for instance, can be experimentally tuned by means of the solvent polarity. Here, our findings indicate that the singlet fission yield can be doubled, while the electronic coherence time t0 is mainly unaffected.

Real-time non-adiabatic dynamics in the one-dimensional Holstein model: Trajectory-based vs exact methods

“…The recently introduced projected-purification method 93 might be another avenue towards reaching longer times, but time-dependent simulations of this method have not been systematically explored yet (see Ref. 106 for an application). Extensions of DMRG or generalizations of matrixproduct states to two-dimensional systems exist, 90,91,[189][190][191][192][193] yet are more expensive algorithms and combinations with efficient treatments of phonons have not been attempted or systematically tested.…”

“…86,88,[96][97][98][99][100][101][102] Naturally, one can ask if the approximate methods devised for quantum chemistry could be applied in condensed matter 57,[103][104][105] and vice versa. 106 To answer such questions, benchmarks, such as the ones that have been carried out in the context of cavity QED 78 or the spin-boson model, 57,107 are desirable. We also mention a recent comparative study of several quantum-chemistry methods performed in large chromophores.…”

Quintet formation and exchange fluctuations: The role of stochastic resonance in singlet fission

“…The considered open quantum system formulation of singlet fission, similar to that of Refs. [12,32,54], is also powerful tool for the quantitative study of spin-mixing in singlet fission for specific materials, and can be generalised to account for spin-orbit coupling, spin migration, and other phenomena. It also provides the natural mathematical framework to implement coherent control tasks like fiducial state preparation, that can be tackled using quantum optimal control protocols [55][56][57], and, possibly, saturate bounds for time-optimal state preparation [11,58].…”

Finite-temperature optical conductivity with density-matrix renormalization group methods for the Holstein polaron and bipolaron with dispersive phonons

“…One drawback of DMRG is the unfavorable scaling for systems with a large local Hilbert space, as is the case for the Holstein model. For this reason, several schemes to treat these systems more efficiently have been suggested [82][83][84][85]. In Ref [35], we successfully combined the finite-temperature method of purification [73] with tDMRG [74] and local basis optimization (LBO) [82] to compute several spectral functions of the Holstein-polaron model.…”