The discussion here is divided into two major sections. First, we discuss the benchmarking of DFT and wavefunction-based methods on SH 2+•• . We have utilized the standard BS-DFT method and compared the 2J values calculated by various exchange-correlation functionals with the experimental result. Besides this, spin-constrained DFT and SF-TDDFT calculations were also carried out. For wavefunction-based calculations, the CASSCF+NEVPT2 method was utilized. Here, the choice of active space is critical for the precise calculation of 2J. The process of choosing the active space has been discussed in detail in this section.