Composite model chemistry methods involve a stepwise approach to obtain accurate results in chemical calculations. These methods begin with initial calculations at a relatively simple and cost-effective level. The basis set is then extended to the complete basis set (CBS) limit, and higher levels of correlation energy, such as MP4 and perturbative triples excitations, are incorporated. Additionally, in some cases, empirical factors are added to correct for dissociation energies with respect to the atoms. By following this approach, composite model chemistry methods can improve the accuracy of chemical calculations without requiring highly expensive computational resources. Available methods comprise the CBS model chemistries reported by Petersson et al. , the Gaussian-n (Gn) methods reported by Pople and co-workers , the Weizmann-n (Wn) theories reported by Martin and co-workers , the focal point method reported by Schuurman et al. , the "high accuracy extrapolated ab initio thermochemistry" (HEAT) method reported by Tajti et al. , and "cheap" schemes (ChS) methods by Barone and coworkers . In particular, in this paper, we used the CBS-QB3, G4 and junChS methods. The junChS total electronic energies are obtained by single-point computations at revDSD-PBEP86-D3(BJ)/jun-cc-pVTZ ge-ometries :