Schouten Anna O, Sager LeeAnn M, Mazziotti David A
Department of Chemistry and The James Franck Institute, The University of Chicago, Chicago, Illinois 60637, United States.
J Phys Chem Lett. 2021 Oct 14;12(40):9906-9911. doi: 10.1021/acs.jpclett.1c02368. Epub 2021 Oct 6.
Recent experiments have realized the Bose-Einstein condensation of excitons, known as exciton condensation, in extended systems such as bilayer graphene and van der Waals heterostructures. Here we computationally demonstrate the beginnings of exciton condensation in multilayer, molecular-scale van der Waals stacks composed of benzene subunits. The populations of excitons, which are computed from the largest eigenvalue of the particle-hole reduced density matrix (RDM) through advanced variational RDM calculations, are shown to increase with the length of the stack. The large eigenvalue indicates a nonclassical long-range ordering of the excitons that can support the frictionless flow of energy. Moreover, we use chemical substitutions and geometric modifications to tune the extent of the condensation. Results suggest exciton condensation in a potentially large family of molecular systems with applications to energy-efficient transport.
近期的实验已在诸如双层石墨烯和范德华异质结构等扩展系统中实现了激子的玻色-爱因斯坦凝聚，即激子凝聚。在此，我们通过计算证明了由苯亚基组成的多层分子尺度范德华堆叠中激子凝聚的开端。通过先进的变分约化密度矩阵（RDM）计算，从粒子-空穴约化密度矩阵的最大本征值计算得到的激子布居数，显示出随堆叠长度增加。这个大本征值表明激子存在非经典的长程有序，能够支持能量的无摩擦流动。此外，我们使用化学取代和几何修饰来调节凝聚程度。结果表明，在一个潜在的大型分子系统家族中存在激子凝聚，这在节能传输方面具有应用前景。
