“…For this method, the standard basis set 6-311+G* was used on the C, O and S atoms and Stuttgart/Dresden relativistic effective core potential (ECP) basis set SDD [8] was used on the Zr atom and this method is denoted as CCSD(T)/SDD+6-311+G*. Our recently studies [9][10][11][12] on some transition-metal contained systems show that single-point CCSD(T) energy calculations are considerable to improve the relative energies. All energies of stationary points described in the following text refer to the relative Fig.…”