The size-dependent structures and optical properties of CdSeS nanoclusters in water medium are investigated. The stability of different size-dependent CdnSemSp
Nearby in the stack
nanoclusters (up to n=6) is studied using density functional theory/time-dependent density functional theory (DFT/TDDFT). The computed results for ground (S
0
) and excited (S
1
, S
2
, S
3
) states are experimentally verified through UV-Vis spectroscopy. Computed ab initio results suggest that CdSeS clusters are significantly more hyperpolarizable compared to CdX (X= S, Se, Te) clusters. Structure dependent response properties are also observed, especially for n>3. Larger hyperpolarizabilities (
β
and
γ
), charge variation and orbital analysis establish Cd
4
Se
m
S
p
clusters, as nonlinear optically active quantum dots (QDs).