Quantum Chemical Design of Molecular Magnets

ended

A reliable ab initio description of molecular magnets is key to developing a new era of quantum devices that will be more efficient and easier to tune by structural modification of their building units. However, quantum mechanical treatment of such systems is challenging due to their multi-configurational wavefunctions, requiring a well balanced description of their constituent electronic configurations. Furthermore, these systems are often large magnetic molecules or atoms deposited on supports whose models include hundreds of atoms, hampering the application of accurate ab initio methods; yet small energy gaps (from tens to hundreds of wavenumbers) call for quantitative accuracy. The aim of this project is to design new molecular magnets, practical for real-world applications. To this end, I will employ a new and affordable computational strategy that combines accurate equation-of-motion coupled-cluster (EOM-CC) theory on the magnetic center with more approximate density functional theory (DFT) on the remainder, avoiding costly EOM-CC calculations on the full system. I will combine interdisciplinary approaches, EOM-CC-in-DFT for open-shell species and tools computing magnetic properties from ab initio calculations, to determine how microscopic interactions (spin-orbit and Zeeman) contribute to macroscopic magnetic properties and how these are optimized in two model systems: (i) a cobalt(II) single-molecule magnet and (ii) single cobalt atoms on the MgO(001) and Cu(111) surfaces. This project will enable, through collaboration between researchers with complementary expertise, a transfer of knowledge across multiple fields, such as solid-state physics, quantum chemistry, and molecular magnetism. Via research training including a secondment, I will explore new approaches; e.g. modelling metal surfaces, periodic wavefunction theories, and periodic embedding theories, which will be crucial to cultivating my place as an expert in this field.