Departament de Química Física and Institut de Química Teòrica i Computacional, Universitat de Barcelona, E-08028 Barcelona, Spain.
J Chem Phys. 2011 Feb 14;134(6):064511. doi: 10.1063/1.3536501.
We explore the excited state energy landscape of small polyhedral zinc sulfide clusters (Zn(4)S(4) and Zn(6)S(6)) using time-dependent density functional theory and correlated wave function based methods. We predict the optical absorption and photoluminescence spectra of the polyhedral clusters and demonstrate that, upon relaxation of the excited state, these nanostructures break symmetry and an electron and a hole localize on a small number of Zn (electron) and S (hole) centers. We further test several exchange-correlation potentials for their ability to recover the correlated wave function description of the excited state. Finally, we discuss how the degeneracy of excited states in nanostructures, such as those considered here, results in a Jahn-Teller distortion of the excited state geometry, and how numerical problems arising from this can be circumvented by starting the optimization of excited states from structures distorted along the ground state vibrational normal modes.
我们使用含时密度泛函理论和相关波函数方法研究了小多面体形锌硫化物团簇（Zn(4)S(4) 和 Zn(6)S(6)）的激发态能量景观。我们预测了多面体形团簇的光吸收和光致发光光谱，并证明在激发态弛豫后，这些纳米结构会破坏对称性，电子和空穴定域在少数 Zn（电子）和 S（空穴）中心上。我们进一步测试了几种交换关联势，以评估它们恢复激发态相关波函数描述的能力。最后，我们讨论了在纳米结构中，例如这里所考虑的那些，激发态的简并如何导致激发态几何的 Jahn-Teller 畸变，以及如何通过从沿着基态振动正则模式扭曲的结构开始优化激发态来避免由此产生的数值问题。
