Structural and static electric response properties of highly symmetric lithiated silicon cages: Theoretical predictions

• Published in: Journal of computational chemistry 2012-04, Vol.33 (10), p.1068-1079
• Main Authors: Koukaras, Emmanuel N., Zdetsis, Aristides D., Karamanis, Panaghiotis, Pouchan, Claude, Avramopoulos, Aggelos, Papadopoulos, Manthos G.
• Format: Article
• Language: English
• Subjects: Atoms & subatomic particles; cage clusters; Chemical Sciences; clusters; Electric properties; fullerenes; Fullerenes - chemistry; hyperpolarizability; Lithium - chemistry; Models, Molecular; Molecular chemistry; or physical chemistry; Quantum Theory; Silicon; Silicon Compounds - chemistry; Static Electricity; Theoretical and
• ISSN: 0192-8651; 1096-987X
• DOI: 10.1002/jcc.22938

It is shown by density functional theory calculations that high symmetry silicon cages can be designed by coating with Li atoms. The resulting highly symmetric lithiated silicon cages (up to D5d symmetry) are low‐lying true minima of the energy hypersurface with binding energies of the order of 4.6 eV per Si atom and moderate highest occupied molecular orbital–lowest unoccupied molecular orbital gaps. Moreover, relying on a systematic study of the electric response properties obtained by ab initio (Hartree–Fock, MP2, and configuration interaction singles (CIS)) and density functional (B3LYP, B2PLYP, and CAM‐B3LYP) methods, it is shown that lithium coating has a large impact on the magnitude of their second hyperpolarizabilities resulting to highly hyperpolarizable species. Such hyperpolarizable character is directly connected to the increase in the density of the low‐lying excited states triggered by the interaction between the Si cage and the surrounding Li atoms. © 2012 Wiley Periodicals, Inc.