Dynamic second-order hyperpolarizabilities of Si2C and Si3C clusters using coupled cluster singles-and-doubles response approach

We investigate the dynamic second-order hyperpolarizabilities γ(−3ω; ω, ω, ω) (indicated by γTHG) of the Si2C and Si3C clusters using the highly accurate coupled cluster singles-and-doubles (CCSD) response approach. The static γ values of the Si2C and Si3C clusters are 1.99 × 10−35 and 3.16 × 10−35 esu, respectively. Similar to the α values, the γ values of the Si2C and Si3C clusters are smaller than those of the Si3 and Si4 clusters, respectively, which is related to much smaller static γ value of the C atom than the Si atom.