Excimer/dimer luminescence is always manifested as a broad, Gaussian-like band at longer wavelengths than the much more narrowband and vibronic PL of the isolated molecule. The most popular way to determine excited state energy is by using the PL onset, but this information is rarely available from the literature. One may note that the long wavelength MMLCT band resembles Gaussian curve to such extent, that the curve can be used as an excellent model for the key regions of the spectrum: onset and maximum (Fig. .1). A simple mathematical analysis of the Gaussian fit yields an accurate spectrum onset value (see ESI Section 2 for mathematical details). Plotting onset against peak energy (Fig. ) reveals an excellent proportional correlation (r 2 = 0.95) between the two quantities, with an offset of 0.333 eV. This relationship demonstrates that all studied PL spectra have a very similar shape in the energy scale and that both: peak and onset are equally representative for the energy of the excited state. One would expect the T1 of the isolated molecule to correlate with that of the excited state dimer. One could then consider an alternative approach for predicting excimer energy using computed T1 energy of the isolated molecule. However, peak energy of excimer and isolated molecule give a very weak correlation (r 2 = 0.6, Fig. ), hence this approach would be inferior to that presented in this work. DFT/TDDFT and Orca 27 software package are used to understand the correlation between experimental excited triplet state (T1) energy of bimolecular states and its computational value. In order to accurately account for long range interactions atom-pairwise dispersion correction with the Becke-Johnson damping scheme (D3BJ) is applied. At first, ground state of individual molecules is optimised using B3LYP/def2-SVP and thus obtained structures are used to construct syn and anti excited state dimers (Fig. ) by placing them in parallel to each other at a distance of roughly 3 Å between the Pt(II) centres. Syn and anti configurations refer to the molecules with identical sides adjacent to each other (syn) or antiparallel (anti). Note that due to a crowded structure of dinuclear complexes 22 and 23 their syn configurations are not obtained. Thus created initial geometries are subsequently optimised at the T1 geometry using BP86/def2-SVP with the said dispersion correction. One can easily note that while all anti configurations present a clear correlation with experimental data (r 2 > 0.85), syn configurations give a very low quality fit (r 2 < 0.45). This is a likely sign that real-life complexes align in an anti configuration with reduced magnitude of interactions between adjacent fragments of the cyclometallating or auxiliary ligand. In other words: syn configuration is a bad model for the experimental behaviour of bimolecular excited states, therefore only anti configuration will be considered from now on. Interestingly, the geometry of the T1 dimer of complex 17 as the only one in the set converges to roughly the same syn configuration regardless of the starting parameters. Generally speaking, use of the B3LYP functional is preferred over BP86 for T1 energy and the combination of BP86/def2-SVP for geometry relaxation and B3LYP/def2-SVP for single point energy appears optimal. The use of solvent model should lead to more accurate predictions than without it. However, the solvatochromic effect on the excited bimolecular states involving platinum(II) complexes is generally small. The approach used in this work allows to offset the solvent effects, leading to generally similar correlation with and without the CPCM. In the particular case of this work the CPCM adds additional noise to the data. Despite similar r 2 for the results obtained using BP86/def2-SVP/B3LYP/def2-SVP with and without the CPCM, the distribution of data points around the trendline is more regular when the solvent model is not used. Only the correlation without CPCM will be used from now on. Simulation of the MMLCT triplet excited state, responsible for experimental behaviour of bimolecular states, with TDDFT requires a close contact between the two metal centres.