We performed static explorations of excited-state potential energy surfaces using the spin-component scaling variant of the algebraic diagrammatic construction to the second order method (SCS-ADC(2)). The SCS-ADC(2) variant was recently shown to provide a more accurate description of excited-state energies and potential energy surfaces of heteroaromatic systems (e.g. nucleobases) when compared with the more standard ADC(2)-s approach.(50) Consequently, we performed all excited-state energy calculations and geometry optimizations at the SCS-ADC(2) level of theory, whereas ground-state energies and geometries were obtained with the equivalent SCS-MP2 approach. For all these calculations we also used the cc-pVDZ-F12 basis set, which although dedicated to explicitly correlated methods, was recently demonstrated to provide excited-state energies and properties with the accuracy of the aug-cc-pVTZ basis set or larger at a lower computational cost.(51) Notably, the cc-pVNZ-F12 basis sets contain more valence functions than included in the conventional cc-pVNZ series in addition to a minimal subset of diffuse functions, which ensure better convergence of Hartree-Fock energy as well as correlation energy, and better overall description of molecular properties. The minimum-energy crossing points between different electronic states were optimized using the approach of Levine and coworkers and the SCS-ADC(2) and SCS-MP2 methods were used to calculate excited-state energies and gradients of the electronic excited states and the ground state, respectively. In particular, previous work demonstrated that the optimizations of state crossings at the ADC(2)/MP2 level offered accurate geometries of S 1 (ππ*)/S 0 minimum-energy crossing points in bioorganic chromophores, which are the primary state crossings considered in this work. Our target compound also does not contain any carbonyl groups, which were recently shown to hinder the correct description of the topography of S1/S0 state crossings with ADC(2) and related methods. The excited-state potential energy (PE) profiles were constructed with linear interpolation in internal coordinates between the key stationary points on the potential energy surface, that is, the Franck-Condon regions, S 1 minima and S 1 /S 0 minimum energy crossing points (MECPs). Only in the case of the C6-puckering mechanism of 9H 2,6-dAP, we performed a minimum-energy path calculation on the S 1 PE surface between the C2-puckered and C6-puckered S 1 minima, using the woelfling module of the Turbomole program and the SCS-ADC(2)/cc-pVDZ-F12 level of theory. To further validate the accuracy of our SCS-ADC(2) calculations we performed single point energy calculations for five primary photorelaxation pathways and the associated potential energy surfaces using the NEVPT2/SA-CASSCF method and the def2-TZVP basis set. These results are presented in Fig. in the ESI and the orbitals included in the active spaces are presented therein. Overall, the active space for all calculations of singlet photorelaxation mechanisms included 8 electrons correlated in 8 orbitals (4 occupied π and 4 virtual π* orbitals), while for the triplet photorelaxation mechanism of the 7H tautomer of 2,6-dAP we applied a somewhat smaller active space including 8 electrons correlated in 6 orbitals (4 occupied π and 2 virtual π* orbitals). These active spaces allowed us to maintain orbital populations between 0.02 and 1.98 and avoid orbital rotation for all studied photorelaxation pathways. Finally, the spin-orbit coupling (SOC) matrix elements between the S1 and T2 electronic states of 7H 2,6-dAP was computed with the CASPT2/SA-CASSCF method with 6 electrons correlated in 5 orbitals and the state-averaging procedure for lowest-energy singlet states and 3 lowest-energy triplet states. In order to account for scalar relativistic effects in our SOC calculations we applied the cc-pVTZ-DK basis set and the the 2 nd order Douglas-Kroll-Hess Hamiltonian. All the SCS-ADC(2) and SCS-MP2 calculations were performed using the Turbomole 7.3 program( ), whereas we used the Molcas 8.4 program (59) for the CASPT2/SA-CASSCF calculations of SOC matrix elements.