SPINOCCHIO · A Quantum Chemical Approach to Spins on Surfaces

Molecules and atoms with unpaired electrons exhibit a net magnetic moment and serve as the building blocks of molecular quantum devices for next-generation technologies. As the design principles for long-lived molecular magnets become clearer, the next challenge is assembling these units into spin lattices via surface deposition and addressing their magnetic behavior at the single-molecule level. Advancing molecular quantum technologies requires understanding the electronic structure and magnetic properties of these building blocks and their interactions with the environment; thus, it depends on quantum chemical calculations. However, our current theoretical toolkit for molecular magnetic materials is inadequate. Density functional theory fails to capture strong correlation, while wave function-based methods are computationally prohibitive for strongly-correlated materials. SPINOCCHIO aims to change this and advance our understanding of the static and dynamic behavior of spins on surfaces and surface spin arrays. These systems, which represent real molecular quantum devices comprising hundreds of atoms and multiple magnetic centers, pose a huge dilemma in quantum chemistry between system size and complexity. To overcome this challenge, we will develop a new quantum chemical approach that combines periodic quantum embedding with a coarse-grained treatment of strong correlation. Equipped with these new tools, we will investigate how the surface affects the magnetic behavior and spin relaxation of the magnetic adsorbate. Moreover, we will explore all light-induced phenomena key to the optical control of individual spins. This newly gained knowledge will guide the design of magnetically stable and optically addressable spins on surfaces, bringing molecular quantum technologies to fruition.