Multi-layer multi-configuration time-dependent Hartree (ML-MCTDH) approach to the correlated exciton-vibrational dynamics in the FMO complex

Abstract

The coupled quantum dynamics of excitonic and vibrational degrees of freedom is investigated for high-dimensional models of the Fenna-Matthews-Olson complex. This includes a seven- and an eight-site model with 518 and 592 harmonic vibrational modes, respectively. The coupling between local electronic transitions and vibrations is described within the Huang-Rhys model using parameters that are obtained by discretization of an experimental spectral density. Different pathways of excitation energy flow are analyzed in terms of the reduced one-exciton density matrix, focussing on the role of vibrational and vibronic excitations. Distinct features due to both competing time scales of vibrational and exciton motion and vibronically assisted transfer are observed. The question of the effect of initial state preparation is addressed by comparing the case of an instantaneous Franck-Condon excitation at a single site with that of a laser field excitation.

Engineering Vibrationally Assisted Energy Transfer in a Trapped-Ion Quantum Simulator

“…Extending our experimental platform, it may be possible to encode the 10-site dynamics of our model in a 10-ion crystal, thereby outperforming bruteforce classical computation. More sophisticated numerical techniques for simulating vibrational wave-packet dynamics have been developed recently, e.g., the multilayer multiconfiguration time-dependent Hartree method (ML-MCTDH) [27]. While such methods substantially reduce the computational burden of computing nonequilibrium dynamics substantially, their computational cost is still exponential with the number of vibrational modes tracked; hence, they eventually scale badly.…”

Computing vibrational eigenstates with tree tensor network states (TTNS)

“…21,22 With ML-MCTDH, scientists were able to simulate model systems with more than 1000 dimensions. 10,12,[23][24][25] Independently, related tensor decompositions have also been developed in condensed matter physics, electronic structure theory and other fields. 21,22,26,27 In particularly successful in these fields is the density matrix renormalization group (DMRG).…”

Vibronic coupling models for donor-acceptor aggregates using an effective-mode scheme: Application to mixed Frenkel and charge-transfer excitons in oligothiophene aggregates

“…The explicit theoretical treatment of photoinduced quantum dynamics of molecular aggregates is a current issue in many fields of biological, chemical, and materials science. 1,2 Examples are the photophysics of DNA fragments, 3,4 light-harvesting systems, 5,6 and other complexes of biological importance. Another class of relevant systems are conjugated polymer materials, especially in view of their use in organic electronics.…”