Dissociation of ZnO ring from Zn3O3 cluster by CASSCF

[Display omitted] •The study focus on a Zn3O3 shield-like ring cluster.•Calculating and analyzing the first excited singlet and triplet.•First time performed the complete active space self-consistent field (CASSCF) method.•First time theoretically two ionic fragments have been reported. Dissociation of a Zn3O3 ring has been theoretically studied in the present work. For this, the complete active space self-consistent field (CASSCF) method with many-body perturbation simulation has been performed. Scan between two atoms from 1.4 Å to 2.5 Å was taken for analyzing active and CASSCF energies with total system energy. This work reveals the theoretical behavior in an absorption corresponding to the first excited singlet and triplet states concerning the dissociation of the ring. The excited states reporting the changes and the change in the gap between them as an effect of breaking the shield type ring.