Bokareva O S, Shibl M F, Al-Marri M J, Pullerits T, Kühn O
Institut für Physik, Universität Rostock , Albert-Einstein-Str. 23-24, 18059 Rostock, Germany.
Gas Processing Center, College of Engineering, Qatar University , P.O. Box 2713, Doha, Qatar.
J Chem Theory Comput. 2017 Jan 10;13(1):110-116. doi: 10.1021/acs.jctc.6b01039. Epub 2016 Dec 29.
The reliable prediction of optical and fundamental gaps of finite size systems using density functional theory requires to account for the potential self-interaction error, which is notorious for degrading the description of charge transfer transitions. One solution is provided by parametrized long-range corrected functionals such as LC-BLYP, which can be tuned such as to describe certain properties of the particular system at hand. Here, bare and 3-mercaptoprotionic acid covered CdSe quantum dots are investigated using the optimally tuned LC-BLYP functional. The range separation parameter, which determines the switching on of the exact exchange contribution, is found to be 0.12 bohr and 0.09 bohr for the bare and covered quantum dot, respectively. It is shown that density functional optimization indeed yields optical and fundamental gaps and thus exciton binding energies, considerably different compared with standard functionals such as the popular PBE and B3LYP ones. This holds true, despite the well established fact that the leading transitions are localized on the quantum dot and do not show pronounced long-range charge transfer character.
使用密度泛函理论可靠地预测有限尺寸系统的光学能隙和基本能隙需要考虑潜在的自相互作用误差，这种误差因会降低电荷转移跃迁的描述质量而声名狼藉。一种解决方案是由诸如LC - BLYP之类的参数化长程校正泛函提供的，这些泛函可以进行调整，以便描述手头特定系统的某些性质。在此，使用经过最佳调整的LC - BLYP泛函研究了裸露的和3 - 巯基丙酸包覆的CdSe量子点。发现决定精确交换贡献开启的范围分离参数，对于裸露的量子点和包覆的量子点分别为0.12玻尔和0.09玻尔。结果表明，与诸如流行的PBE和B3LYP等标准泛函相比，密度泛函优化确实产生了光学能隙和基本能隙，从而得到了显著不同的激子结合能。尽管已经确定主要跃迁定域在量子点上且不显示明显的长程电荷转移特征，但情况依然如此。
