  In this paper we investigate the role of electron correlation in predicting
the S$_1$-S$_0$ and T$_1$-S$_0$ excitation energies and hence, the
singlet-triplet gap ($\Delta$E$_{ST}$) in a set of cyclazines which act as
templates for potential candidates for 5th generation Organic Light Emitting
Diode (OLED) materials. This issue has recently garnered much interest with the
focus being on the inversion of the $\Delta$E$_{ST}$, although experiments have
indicated near degenerate levels with both positive and negative being within
the experimental error bar (\emph{J. Am. Chem. Soc. 1980, 102: 6068 , J. Am.
Chem. Soc. 1986, 108: 17} ). We have carried out a systematic and exhaustive
study of various excited state electronic structure methodologies and
identified the strengths and shortcomings of the various approaches and
approximations in view of this challenging case. We have found that near
degeneracy can be achieved either with a proper balance of static and dynamic
correlation in multireference theories or with state-specific orbital
corrections including its coupling with correlation. The role of spin
contamination is also discussed. Eventually, this paper seeks to produce
benchmark numbers for establishing cheaper theories which can then be used for
screening derivatives of these templates with desirable optical and structural
properties. Additionally we would like to point out that the use of
DLPNO-STEOM-CCSD as the benchmark for $\Delta$E$_{ST}$ (as used in \emph{J.
Phys. Chem. A 2022, 126: 8: 1378, Chem. Phys. Lett. 2021, 779: 138827}) is not
a suitable benchmark for this class of molecules.
