Ghazanfari Sarah, Han Yulun, Xia Wenjie, Kilin Dmitri S
Department of Civil, Construction, and Environmental Engineering, North Dakota State University, Fargo, North Dakota 58108, United States.
Department of Chemistry and Biochemistry, North Dakota State University, Fargo, North Dakota 58108, United States.
J Phys Chem Lett. 2022 May 19;13(19):4257-4262. doi: 10.1021/acs.jpclett.2c00697. Epub 2022 May 6.
A theoretical investigation is conducted to describe optoelectronic properties of Fe-doped montmorillonite nanoclay under spin states of low spin (LS), intermediate spin (IS), and high spin (HS). Ground state electronic properties are studied using spin-polarized density functional theory calculations. The nonradiative and radiative relaxation channels of charge carriers are studied by computing nonadiabatic couplings (NACs) using an "on-the-fly" approach from adiabatic molecular dynamics trajectories. The NACs are further processed using a reduced density matrix approach with the Redfield formalism. The computational results are presented for electronic density of states, absorption spectra, charge carrier dynamics, and photoluminescence (PL) by comparing various spin multiplicities. Results on spin α and spin β components are independent and quite different because of the partial occupation of Fe 3d states. Overall, HS is the most stable with the largest Fe-O distances. One finds different nonradiative relaxation pathways in space and on the time scale for electrons and holes. The Redfield PL reveals obvious Fe 3d-3d transitions for LS and IS.
进行了一项理论研究，以描述低自旋（LS）、中自旋（IS）和高自旋（HS）状态下铁掺杂蒙脱石纳米粘土的光电性质。使用自旋极化密度泛函理论计算研究基态电子性质。通过使用来自绝热分子动力学轨迹的“即时”方法计算非绝热耦合（NACs），研究了电荷载流子的非辐射和辐射弛豫通道。使用具有雷德菲尔德形式的约化密度矩阵方法对NACs进行进一步处理。通过比较各种自旋多重性，给出了态密度、吸收光谱、电荷载流子动力学和光致发光（PL）的计算结果。由于Fe 3d态的部分占据，自旋α和自旋β分量的结果是独立的且有很大差异。总体而言，HS最稳定，Fe-O距离最大。人们发现电子和空穴在空间和时间尺度上有不同的非辐射弛豫途径。雷德菲尔德PL揭示了LS和IS明显的Fe 3d-3d跃迁。
