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

► The highly accurate coupled cluster singles-and-doubles (CCSD) response approach is employed to calculate the dynamic second-order hyperpolarizabilities γ(−3ω; ω, ω, ω) of the Si2C and Si3C clusters. ► The Si2C and Si3C cluster are potential candidates for THG nonlinear optical materials in the infrared range. ► A comparison is made with the γ values of the Si3 and Si4 clusters.