Remarkably, however, the more stable T 1 (ππ * the thick black curve) crosses with S 1 and T 2 near S 1min , providing a plausible route of IC or ISC. Thus, the most probable initial intersystem crossing (IRC) would be S 1 → T 1 or S 1 → T 3 pathways. While T 1 has a crossing with S 1 at S 1min structure, the T 3 is ∼ 1 eV higher than S 1 along the entire PES. Therefore, the former ISC is more likely to occur. The corresponding SOC values are presented in Fig. . In terms of S 1 /T 1 SOC magnitude, the initial values at FC (10.4 cm -1 ) is increased to 19 cm -1 at BLA=0.19. It is quite significantly decreased afterward to 3 cm -1 . The same trend can be seen from the SOC values of S 1 /T 3 (M s = ±1) curve.