Simulation of the Two-Dimensional Electronic Spectroscopy and Energy Transfer Dynamics of Light-Harvesting Complex II at Ambient Temperature

Abstract

We simulate the two-dimensional electronic spectra (2DES) of the light-harvesting complex II (LHCII) at room temperature by combining the hierarchical equations of motion method and the equation-of-motion phase-matching approach. The laser-excited population dynamics of LHCII is also calculated to help understanding the 2DES. Three different excitation schemes are studied, including (1) only the chlorophyll (Chl) b Q states of LHCII are excited, (2) only the Chl a Q states are excited, and (3) both the Chl b and Chl a states are excited. The energy transfer pathways and time scales revealed from the 2DES in schemes (1) and (2) agree with the recent experimental studies for the Chl b to Chl a energy transfer and the excitation energy relaxation process within the Chl a manifold. We also propose a different way to better present the signals of bottleneck states by investigating the diagonal peaks of the 2DES in scheme (3).

Theoretical study of excitation energy transfer and nonlinear spectroscopy of photosynthetic light‐harvesting complexes using the nonperturbative reduced dynamics method

“…Figure 5 shows the population dynamics on each Chl pigments in the case that the pump laser pulse excites the Chl b manifold. 104 The simulated energy transfer pathways and timescales were found to be in good agreement with the accompanying simulation of the 2DES (Section 5), and the experiment. 107,108…”

“…In a recent work, Leng et al 104 simulated the EET dynamics in the light‐harvesting complex II (LHCII) at room temperature using the HEOM method. LHCII is the most abundant form of light‐harvesting complexes in higher plants, and has attracted many recent studies 10,53,105–107 .…”

“…Laser excited population dynamics of LHCII complex at 298 K 104 . The excitation pulse is centered at 15,385 cm −1 with a time duration of 42 fs.…”

“…For the symmetric dimer, the high energy state carries zero oscillator strength when neglecting the electronic-vibrational coupling. However, a weak peak appears F I G U R E 5 Laser excited population dynamics of LHCII complex at 298 K. 104 The excitation pulse is centered at 15,385 cm −1 with a time duration of 42 fs. (a) The Chlb states.…”

Hierarchical equations of motion in the Libra software package

“…[9][10][11] The HEOM calculations allowed accurate calculations at low temperatures, whereas perturbative approaches such as Redfield [12,13] or Forster [12,14] fail. [15][16][17][18][19][20][21][22] The HEOM has often been used to obtain numerically exact results for spin-Boson problems across several regimes, and it can be used as a reference methodology for other approximate methods [8,[23][24][25] applied to modeling open quantum systems.…”