A theoretical investigation of hyperpolarizability for small Gan Asm (n+m=4-10) clusters

In this paper, the second and third order polarizabilities of small Gan Asm (n+m=4-10) clusters are systematically investigated using the time dependent density functional theory (TDDFT) 6-311+ G* combined with the sum-over-states method (SOSTDDFT6-311+ G*). For the static second order polarizabilities, the two-level term (Βvec.2) makes a significant contribution to the Βvec for all considered Gan Asm clusters except for the Ga3 As4 cluster. And, for the static third order polarizabilities, the positive channel (〈γ〉II) makes a larger contribution to 〈γ〉tot than the negative channel (〈γ〉I). Similar to the cubic GaAs bulk materials, the small Gan Asm cluster assembled materials exhibit large second order (1× 10-6 esu) and third order susceptibilities (5× 10-11 esu). The dynamic behavior of Β (-2ω;ω, ω) and γ (-3ω;ω,ω,ω) show that the small Gan Asm cluster will be a good candidate of nonlinear optical materials due to the avoidance of linear resonance photoabsorption.