The giant magnetic anisotropy energy of Fe+ ions in SrCl2.

We show that values of the magnetic anisotropy energy (MAE), which are about two orders of magnitude larger than the usual ones for transition metal cations in insulators (approximately 0.01-1 cm(-1)), can be found for the less common ion Fe+. In SrCl2:Fe+, the MAE is 93 cm(-1) when calculated using second-order perturbation multi-configurational calculations (CASPT2) while a similar value is found using multi-reference density functional theory (MR-DFT).

Theoretical study of the geometrical and electronic structures and thermochemistry of spherophanes.

A set of supramolecular cage-structures--spherophanes--was studied at the density functional B3LYP level. Full geometrical structure optimisations were made with 6-31G and 6-31G(d) basis sets followed by frequency calculations, and electronic energies were evaluated at B3LYP/6-31++G(d,p). Three different symmetries were considered: C1, Ci, and Oh.

Combined ligand field and density functional theory analysis of the magnetic anisotropy in oligonuclear complexes based on Fe(III)-CN-M(II) exchange-coupled pairs.

Magnetic anisotropy in cyanide-bridged single-molecule magnets (SMMs) with Fe(III)-CN-M(II) (M = Cu, Ni) exchange-coupled pairs was analyzed using a density functional theory (DFT)-based ligand field model. A pronounced magnetic anisotropy due to exchange was found for linear Fe(III)-CN-M(II) units with fourfold symmetry. This results from spin-orbit coupling of the [Fe(III)(CN)6](3-) unit and was found to be enhanced by a tetragonal field, leading to a (2)E g ground state for Fe(III).

DFT-based studies on the Jahn-Teller effect in 3d hexacyanometalates with orbitally degenerate ground states.

The topology of the ground-state potential energy surface of M(CN)(6) with orbitally degenerate (2)T(2g) (M = Ti(III) (t(2g)(1)), Fe(III) and Mn(II) (both low-spin t(2g)(5))) and (3)T(1g) ground states (M = V(III) (t(2g)(2)), Mn(III) and Cr(II) (both low-spin t(2g)(4))) has been studied with linear and quadratic Jahn-Teller coupling models in the five-dimensional space of the epsilon(g) and tau(2g) octahedral vibrations (Tg[symbol: see text](epsilon(g)+tau(2g)) Jahn-Teller coupling problem (T(g) = (2)T(2g), (3)T(1g))). A procedure is proposed to give access to all vibronic coupling parameters from geometry optimization with density functional theory (DFT) and the energies of a restricted number of Slater determinants, derived from electron replacements within the t(2g)(1,5) or t(2g)(2,4) ground-state electronic configurations. The results show that coupling to the tau(2g) bending mode is dominant and leads to a stabilization of D(3d) structures (absolute minima on the ground-state potential energy surface) for all complexes considered, except for [Ti(CN)(6)](3-), where the minimum is of D(4h) symmetry.

Intramolecular spin alignment in photomagnetic molecular devices: a theoretical study.

Ground- and excited-state magnetic properties of recently characterized pi-conjugated photomagnetic organic molecules are analyzed by the means of density functional theory (DFT). The systems under investigation are made up of an anthracene (An) unit primarily acting as a photosensitizer (P), one or two iminonitroxyl (IN) or oxoverdazyl (OV) stable organic radical(s) as the dangling spin carrier(s) (SC), and intervening phenylene connector(s) (B). The magnetic behavior of these multicomponent systems, represented here by the Heisenberg-Dirac magnetic exchange coupling (J), as well as the EPR observables (g tensors and isotropic A values), are accurately modeled and rationalized by using our DFT approach.

DFT studies on the magnetic exchange across the cyanide bridge.

Exchange coupling across the cyanide bridge in a series of novel cyanometalate complexes with CuII-NC-MIII (M = Cr and low-spin Mn, Fe) fragments has been studied using the broken-symmetry DFT approach and an empirical model, which allows us to relate the exchange coupling constant with sigma-, pi-, and pi*-type spin densities of the CN- bridging ligand. Ferromagnetic exchange is found to be dominated by pi-delocalization via the CN- pi pathway, whereas spin polarization with participation of sigma orbitals (in examples, where the dz2 orbital of MIII is empty) and pi* orbitals of CN- yields negative spin occupations in these orbitals, and reduces the CuII-MIII exchange coupling constant. When the dz2 orbital of MIII is singly occupied, an additional positive spin density appears in the sigma(CN) orbital and leads to an increase of the ferromagnetic Cu-NC-M exchange constant.

Effect of the f-Orbital Delocalization on the Ligand-Field Splitting Energies in Lanthanide-Containing Elpasolites.

The ligand-field induced splitting energies of f-levels in lanthanide-containing elpasolites are derived using the first-principles universal orbital-free embedding formalism [Wesolowski and Warshel, J. Phys. Chem.

Density Functional Description of the Ferromagnetic Exchange Interactions between Semiquinonato Radicals Mediated by Diamagnetic Metal Ions.

The electronic structures of Ti(CatNSQ)(2) and Sn(CatNSQ)(2), where CatNSQ(2)(-) is the tridentate radical ligand (3,5-di-tert-butyl-1,2-semiquinonato 1(2-hydroxy-3,5-di-tert-butyl-phenyl)immine), were investigated with density functional (DF) calculations, using the local approximation for the exchange-correlation functional. The crystal structure of Sn(CatNSQ)(2) was solved. The complex crystallizes in the orthorhombic space group, C222(1), with Z = 8 in a unit cell of the following dimensions: a = 19.