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First-principles quantum simulations of exciton diffusion on a minimal oligothiophene chain at finite temperature.
Faraday Discussions ( IF 3.4 ) Pub Date : 2019-12-16 , DOI: 10.1039/c9fd00066f
Robert Binder 1 , Irene Burghardt
Affiliation  

High-dimensional multiconfigurational quantum dynamics simulations are carried out at finite temperature to simulate exciton diffusion on an oligothiophene chain, representative of a segment of the poly(3-hexylthiophene) (P3HT) polymer. The ab initio parametrized site-based Hamiltonian of Binder et al. [Phys. Rev. Lett., 2018, 120, 227401] is employed to model a 20-site system, including intra-ring and inter-ring high-frequency modes as well as torsional modes which undergo thermal fluctuations induced by an explicit harmonic oscillator bath. The system-bath dynamics is treated within the setting of a stochastic mean-field Schrödinger equation. For the 20-site excitonic system, a total of 20 Frenkel states and 248 modes are propagated using the multi-layer multi-configuration time-dependent Hartree (ML-MCTDH) method. The resulting dynamics can be interpreted in terms of the coherent motion of an exciton-polaron quasi-particle stochastically driven by torsional fluctuations. This dynamics yields a near-linear mean squared displacement (MSD) as a function of time, from which a diffusion coefficient can be deduced which increases with temperature, up to 5.7 × 10-3 cm2 s-1 at T = 300 K.

中文翻译:

有限温度下最小寡聚噻吩链上激子扩散的第一性原理量子模拟。

在有限的温度下进行高维多构型量子动力学模拟,以模拟激子在低聚噻吩链上的扩散,该聚噻吩链代表聚(3-己基噻吩)(P3HT)聚合物的一部分。Binder等人从头算起基于参数的哈密顿量。[物理 Rev. Lett。,2018,120,227401]用于模拟20个站点的系统,包括环内和环间高频模式以及发生由明确谐波振荡器浴引起的热波动的扭转模式。系统浴动力学在随机平均场Schrödinger方程的设置范围内进行处理。对于20个位置的激子系统,使用多层多配置时变哈特里(ML-MCTDH)方法传播总共20个Frenkel状态和248个模式。所产生的动力学可以根据扭振起伏随机驱动的激子-极化子准粒子的相干运动来解释。这种动力学产生了随时间变化的近线性均方位移(MSD),从中可以得出扩散系数随温度升高而增加,在T = 300 K时可达5.7×10-3 cm2 s-1。
更新日期:2019-12-17
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