Homogeneous Dephasing in Photosynthetic Bacterial Reaction Centers: Time Correlation Function Approach.

Area of Science:

• * Biophysics
• * Physical Chemistry
• * Quantum Biology

Background:

• * Bacterial reaction centers (BRCs) like Rhodopseudomonas viridis are crucial for photosynthesis.
• * Understanding electron-phonon coupling is vital for modeling energy transfer in pigment-protein complexes.
• * Existing frequency-domain methods struggle with strong coupling, high temperatures, and multiple vibrational modes.

Purpose of the Study:

• * To derive a novel, tractable linear electronic transition dipole moment time correlation function (ETDMTCF).
• * To accurately account for electronic dephasing, asymmetry, and phonon profile width, including zero-phonon line contributions.
• * To provide a computationally efficient method for analyzing complex systems and nonlinear optical signals.

Main Methods:

• * Development of a new linear electronic transition dipole moment time correlation function (ETDMTCF).
• * Application of Fourier transform to derive asymmetric multiphonon profiles (Lorentzian and Gaussian distributions).
• * Integration with nonlinear optical response theory and Liouville space pathways for signal computation.

Main Results:

• * The derived ETDMTCF accurately models dephasing, asymmetry, and width of the one-phonon profile.
• * It produces asymmetric multiphonon profiles suitable for strong electron-phonon coupling and high temperatures.
• * The ETDMTCF enables efficient computation of nonlinear optical signals in large systems.

Conclusions:

• * The new ETDMTCF is superior to existing frequency-domain methods for complex photosynthetic systems.
• * It offers significant advantages in computational expediency and accuracy for nonlinear optical signal analysis.
• * The study highlights the intimate connection between phonon profiles and bath spectral densities in photosynthetic complexes.