Spin-related properties, such as SOCs and spin-spin interactions, determine magnetic behavior of molecules, which is central for understanding spectroscopic signatures of unpaired electrons (e.g., EPR spectroscopy), their macroscopic magnetic properties (magnetozabilities), and magnetic relaxation times. The ability to model these properties computationally is a key prerequisite for the design of novel materials. For example, single-molecule magnets (SMMs), molecules with several unpaired electrons that have a high-spin ground state in the absence of an applied magnetic field , can be used as building blocks to create novel, light-weight, and tunable magnetic materials or as building blocks for quantum information storage and quantum computations . The key challenge in realizing the full potential of SMMs is the ability to tune and control their magnetic behavior.