Breather dynamics and the role of near-neighbor coupling in charge transport within the Holstein-SSH DNA model

In this study, we analyze charge transport in the Holstein-SSH DNA lattice model through the analysis of breather dynamics. Using an empirical Holstein-SSH DNA lattice model combined with the quasi-discrete approximation, we have shown that the dynamics of charge transport can be modeled by the nonlinear Schrödinger equation. Analytical study of the modulational instability (MI) phenomenon, based on this equation, revealed that when the nearest-neighbor transfer integral is high, the system becomes more stable, thus offering better charge transport. Furthermore, numerical analysis of MI revealed that our system admits breather solutions, indicating that the stability/instability dynamics can be influenced by the wave number. Subsequently, we derive the breather-type solution and numerically plot its spatio-temporal evolution. One interesting result of this study is that during charge transport in DNA, we find that high values of nearest-neighbor transfer integral could indicate that solitons are more resistant to perturbations or disorder, allowing localized waves to maintain their shape and energy over longer distances. Which allows us to deduce some biological implications linked to charge transport in DNA.