Simplified Models for Accelerated Structural Prediction of Conjugated Semiconducting Polymers
Simplified Models for Accelerated Structural Prediction of Conjugated Semiconducting Polymers
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DOI：
10.1021/acs.jpcc.7b09701
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发表时间：
2017-11-30
影响因子：
3.7
通讯作者：
Jankowski, Eric
中科院分区：
文献类型：
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作者：
Henry, Michael M.;Jones, Matthew L.;Jankowski, Eric
我们进行分子动力学模拟的聚（苯并二噻吩-噻吩并吡咯二酮）（BDT-TPD）低聚物，以评估的准确性，未优化的分子模型可以预测实验表征的形态。预测的形态，其特征在于使用模拟掠入射X射线散射（GIXS）和实验散射模式相比。我们发现，近似的芳香环BDT-TPD与刚体，而不是结合键，角度和二面角的限制，结果在14%的计算成本降低，并提供几乎等同的结构预测相比，灵活的模型的情况下。BDT-TPD的玻璃化转变温度（410 +/- 32 K）的预测被发现与实验一致。预测的形态显示了由于链骨架的堆叠（约3.9埃的π-π堆叠）而产生的短程结构有序性，以及由于骨架堆叠自组织成“带”（约20.9埃的层状有序性）而产生的长程空间相关性，这代表了复杂共轭低聚物结构的最新计算预测。我们发现，昂贵的模拟退火时间表是不需要预测实验结构在这里，与瞬时淬火提供几乎等同的预测在一小部分的退火计算成本。因此，我们建议利用刚性体和快速冷却时间表进行半柔性聚合物和低聚物的高通量筛选研究，以在适当的情况下利用其显着的计算优势。
We perform molecular dynamics simulations of poly(benzodithiophene-thienopyrrolodione) (BDT-TPD) oligomers in order to evaluate the accuracy with which unoptimized molecular models can predict experimentally characterized morphologies. The predicted morphologies are characterized using simulated grazing-incidence X-ray scattering (GIXS) and compared to the experimental scattering patterns. We find that approximating the aromatic rings in BDT-TPD with rigid bodies, rather than combinations of bond, angle, and dihedral constraints, results in 14% lower computational cost and provides nearly equivalent structural predictions compared to the flexible model case. The predicted glass transition temperature of BDT-TPD (410 +/- 32 K) is found to be in agreement with experiments. Predicted morphologies demonstrate short-range structural order due to stacking of the chain backbones (pi-pi stacking around 3.9 angstrom), and long-range spatial correlations due to the self -organization of backbone stacks into "ribbons" (lamellar ordering around 20.9 angstrom), representing the best -to -date computational predictions of structure of complex conjugated oligomers. We find that expensive simulated annealing schedules are not needed to predict experimental structures here, with instantaneous quenches providing nearly equivalent predictions at a fraction of the computational cost of annealing. We therefore suggest utilizing rigid bodies and fast cooling schedules for high -throughput screening studies of semiflexible polymers and oligomers to utilize their significant computational benefits where appropriate.