DFT Calculation of Russell鈥揝aunders Splitting for Lanthanide Ions Doped in Hexagonal (尾)-NaYF4 Nanocrystals

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• 作者：Ge Yao ; Mary T. Berry ; P. Stanley May ; Dmitri Kilin
• 刊名：The Journal of Physical Chemistry C
• 出版年：2013
• 出版时间：August 22, 2013
• 年：2013
• 卷：117
• 期：33
• 页码：17177-17185
• 全文大小：528K
• 年卷期：v.117,no.33(August 22, 2013)
• ISSN：1932-7455

文摘

A systematic investigation is reported of the optimized geometry and electronic structure of trivalent lanthanide ions (Ln<sup>3+sup>) doped in hexagonal (尾)-NaYF<sub>4sub> nanocrystals in the basis of density functional theory with a spin polarization approach. A model Na<sub>24sub>Y<sub>23sub>Ln<sub>1sub>F<sub>96sub> nanocrystal with a single central lanthanide dopant (Ln<sup>3+sup>) is used. Electron spins couple to give a total spin, S, and electron orbital angular momenta couple to give total orbital angular momentum, L. Spin鈥搊rbit coupling is neglected in this initial study. Several key observables are found to be strongly related to the number of unpaired f-electrons in the model. After geometry optimization, the phenomenon of the lanthanide contraction is observed, and the configurations of 4f-electron-like orbitals satisfy Hund鈥檚 Rule under the orbital decomposition. Spin-polarized density functional theory is applied to generate the Russell鈥揝aunders terms (<sup>2S+1sup>L) terms of lanthanide ions. The energy differences between the first and the second terms are calculated and show good agreement with experimental measurements. The free-ion-like behavior of Ln<sup>3+sup> ions in the nanocrystal is observed as well.