Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan.
Center for Spintronics Research Network (CSRN), Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan.
Molecules. 2019 Feb 1;24(3):541. doi: 10.3390/molecules24030541.
We have developed a Monte Carlo wavefunction (MCWF) approach to the singlet fission (SF) dynamics of linear aggregate models composed of monomers with weak diradical character. As an example, the SF dynamics for a pentacene dimer model is investigated by considering the intermolecular electronic coupling and the vibronic coupling. By comparing with the results by the quantum master equation (QME) approach, we clarify the dependences of the MCWF results on the time step (Δ) and the number of MC trajectories (). The SF dynamics by the MCWF approach is found to quantitatively (within an error of 0.02% for SF rate and of 0.005% for double-triplet (TT) yield) reproduce that by the QME approach when using a sufficiently small Δ (0.03 fs) and a sufficiently large (10⁵). The computational time () in the MCWF approach also exhibits dramatic reduction with increasing the size of aggregates (-mers) as compared to that in the QME approach, e.g., ~34 times faster at the 20-mer, and the size-dependence of shows significant reduction from (QME) to (MCWF). These results demonstrate the promising high performance of the MCWF approach to the SF dynamics in extended multiradical molecular aggregates including a large number of quantum dissipation, e.g., vibronic coupling, modes.
我们开发了一种用于单体具有弱双自由基特征的线性聚集体模型的单重态裂变 (SF) 动力学的蒙特卡罗波函数 (MCWF) 方法。例如，通过考虑分子间电子耦合和振子耦合，研究了并五苯二聚体模型的 SF 动力学。通过与量子主方程 (QME) 方法的结果进行比较，我们阐明了 MCWF 结果对时间步长 (Δ) 和 MC 轨迹数 (N) 的依赖性。发现 MCWF 方法的 SF 动力学可以定量地（SF 速率的误差在 0.02%以内，双三重态 (TT) 产率的误差在 0.005%以内）重现 QME 方法的结果，当使用足够小的 Δ（0.03 fs）和足够大的 N（10⁵）时。与 QME 方法相比，MCWF 方法中的计算时间（）随着聚集体（mers）尺寸的增加而显著减少，例如，在 20-mer 时快 34 倍，并且从 （QME）到 （MCWF）， 表现出显著减少。这些结果表明，MCWF 方法在包括大量量子耗散（例如，振子耦合）模式的扩展多自由基分子聚集体中的 SF 动力学具有很高的性能。
