Ab initio investigation on the nonlinear optical properties of silicon clusters Si_{n} (n=3–8)
Titel:
Ab initio investigation on the nonlinear optical properties of silicon clusters Si_{n} (n=3–8)
Auteur:
Champagne, Benoît Guillaume, Maxime Bégué, Didier Pouchan, Claude
Verschenen in:
Journal of computational methods in sciences and engineering
Paginering:
Jaargang 7 (2008) nr. 3-4 pagina's 297-304
Jaar:
2008-04-28
Inhoud:
First and second hyperpolarizabilities of small silicon clusters have been calculated using conventional ab initio methods systematically increasing the amount of electron correlation. Besides Si_{5}, upon successive addition of electron correlation in the MP2, MP3, MP4, CCSD, and CCSD(T) series, all clusters display the same behavior: i) the HF γ _{//} values are the smallest, ii) the MP2 γ _{//} values the largest, and iii) the latter values are good approximate to the reference CCSD(T) results because the overestimation is smaller than 10%. Contrary to the polarizability per Si atom, which decreases with the cluster size until reaching the bulk limit, the average second hyperpolarizability per Si atom presents a sawtooth behavior with maxima in γ _{//} associated with even numbers of Si and minima with odd numbers of Si atoms.