​My PhD thesis is an in-depth study of the magnetic properties of a series of different lanthanide-based endohedral metallofullerenes. They are sphere-like shape carbon molecules (fullerenes) with embedded magnetic lanthanide elements inside, suitable for spintronic and high dense-data storage applications. In this work, I studied two families of endohedral metallofullerenes (di-lanthanides and Dy-oxides) which showed great versatility in the magnetic behavior, depending on the type of the encapsulated cluster, and the size and shape of the carbon cage.:Magnetic studies on lanthanide dimetallofullerenes Gd2@C80(CH2Ph) and Gd2@C79N Tb2@C80(CH2Ph) and Tb2@C79N TbY@C80(CH2Ph) Ho2@C80(CH2Ph) Er2@C80(CH2Ph) Magnetic studies on Dy-oxide clusterfullerenes Dy2O@C72 Dy2O@C74 Dy2O@C82 (three isomers)

This work describes theoretical studies on molecular and electronic structures of lanthanide-based single-molecule magnets focusing on their magnetic properties. In this work, two main problems are covered: the structural ordering of endohedral fullerenes in different supramolecular arrangements, and the magnetic anisotropy of lanthanides in different charge coordinations. The basic methodes used in this work are density functional theory and multiconfigurational self-consistent field.:CHAPTER 1. THEORETICAL FOUNDATIONS OF RARE-EARTH MAGNETISM 12 1.1. Single-molecule magnetism and 4f-elements 14 1.1.1. Electronic structure of 4f-elements 16 1.1.2. LS-coupling scheme 19 1.1.3. Parameterization of the Crystal-Field splitting effect. 20 1.1.4. Zeeman splitting for a free ion 24 1.1.5. Spin Hamiltonian and pseudospin approximation 24 1.1.6. Kramers theorem 25 1.1.7. Weak and strong molecular interactions. 26 1.2. Computational methods in application to Ln-based SMMs 27 1.2.1. Density functional theory (DFT). 28 1.2.2. Multiconfigurational methods in quantum chemistry 33 1.3. Role of molecular structure in single-molecular magnetism 41 1.3.1. Complexes of SMMs with organic molecules 45 1.3.2. SMMs deposited on surfaces 46 CHAPTER 2. STRUCTURAL ORDERING IN COCRYSTALS OF EMFs AND Ni(OEP) 49 2.1. Ordering in endohedral metallofullerenes 49 2.2. Modeling details 51 2.3. Conformer analysis 54 2.4. Electrostatic potential 58 CHAPTER 3. ISOMERISM OF Dy2ScN@C80 DEPOSITED ON SURFACES 61 3.1. Modeling details 62 3.2. Cluster conformation analysis 69 3.3. Charge density analysis 75 CHAPTER 4. Ho|MgO AS A SINGLE-ATOMIC MAGNET. FV-MAGNETISM. 80 4.1. DFT description of Ln|MgO 85 4.2. Ho|MgO system: ab initio calculations 92 4.3. Magnetic properties of lanthanides with FV magnetism 99 4.4. Generalized ligand field and spin Hamiltonians for FV systems. 101 CHAPTER 5. FV-MAGNETISM IN [Ln2+] METALLOCENE COMPLEXES 107 5.1. TbII(CpiPr5)2 DFT-model 108 5.2. FV-interaction in terms of ab initio multiconfigurational approach 113 5.3. Point-charge model 115