The research in this project will involve the usage of modern tools of quantum chemistry for design and characterization of new materials with promising spectroscopic properties for their application in organic electronic devices like organic light emitting diodes (OLEDs), dye-synthesized solar cells (DSSCs), organic field effect transistors (OFETs), thermoelectric converters etc. Our computing activities will be divided into two main areas: 1) Spectroscopy of finite molecular systems (from small molecules to supramolecules); 2) spectroscopy of infinite (periodic) systems based on periodic boundary conditions (PBC) approximation. In collaboration with experimentalist at national and international levels we will investigate the spectroscopic properties of target materials at different conditions and external stimuli in order to get insight on such practically important phenomena like aggregation-induced emission (AIE), mechanoluminescence, room temperature phosphorescence (RTP), thermally activated delayed fluorescence (TADF). We intensively learn and introduce new software for computational spectroscopy modelling being in contact with leading developers in this field and accounting for efficient usage of computational resources through high-performance parallel computing and we plan to continue such activity in the current project. In our studies we will pay special attention to the spectroscopy and magnetism of two dimensional (2D) materials for tailored opto-electronic applications that are in worldwide focus now because of the successful progress in synthesis and characterization of 2D monoelements (graphene, BP, Te, Bi), transition-metal dichalcogenides (TMDs, MoS2, WS2, PtSe2), and transition-metal carbides/nitrides (MXene, Ti4C3, Nb2C, Mo2C). Carrier dynamics and nonlinear optical properties in these materials and their derivatives will also be investigated in this project. We will also investigate new 2D magnets based on materials with strong interlayer coupling for their future implementation in heterostructures and surface modification. Our team for today counts four persons (one postdoc is on the way to Linköping University) all active in performing spectroscopic simulation with different software mostly available on UPPMAX and NSC clusters (like Gaussian 16, Dalton, ORCA, Turbomole, Quantum Espresso, VASP, CP2K, AICD etc.). Thus, in this proposal we request storage resources on UPPMAX, PDC and NSC clusters (with directory name "molspect") at the average level for NAISS Medium Storage 2024 allocation as an addition to our already submitted NAISS Medium Compute 2024 (NAISS 2024/5-73) resources application.