Atanasov, Mihail Comba, Peter Daul, Claude Hauser, Andreas 2007-08-24 The topology of the ground-state potential energy surface of M(CN)₆ with orbitally degenerate ²T_2g (M = Ti^III (t_2g¹), Fe^III and Mn^II (both low-spin t_2g⁵)) and ³T_1g ground states (M = V^III (t_2g²), Mn^III and Cr^II (both low-spin t_2g⁴)) has been studied with linear and quadratic Jahn-Teller coupling models in the five-dimensional space of the ε_g and θ_2g octahedral vibrations (T_g⊗(ε_g+θ_2g) Jahn-Teller coupling problem (T_g = ²T_2g, ³T_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 θ_2g bending mode is dominant and leads to a stabilization of <i>D</i>₃<i>_d</i> 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 <i>D</i>₄<i> _h</i> symmetry. The Jahn-Teller stabilization energies for the <i>D</i>₃<i>_d</i> minima are found to increase in the order of increasing CN-M π back-donation (Ti^III< V^III< Mn^III< Fe^III< Mn^II< Cr^II). With the angular overlap model and bonding parameters derived from angular distortions, which correspond to the stable <i>D</i>₃<i>_d</i> minima, the effect of configuration interaction and spin-orbit coupling on the ground-state potential energy surface is explored. This approach is used to correlate Jahn-Teller distortion parameters with structures from X-ray diffraction data. Jahn-Teller coupling to trigonal modes is also used to reinterpret the anisotropy of magnetic susceptibilities and <b>g</b> tensors of [Fe(CN)₆]³⁻, and the ³T_1g ground-state splitting of [Mn(CN)₆]³⁻, deduced from near-IR spectra. The implications of the pseudo Jahn- Teller coupling due to t_2g-e_g orbital mixing via the trigonal modes (θ_2g) and the effect of the dynamic Jahn-Teller coupling on the magnetic susceptibilities and <b>g</b> tensors of [Fe(CN)₆]³⁻ are also addressed. application/pdf https://folia.unifr.ch/global/documents/300608 https://folia.unifr.ch/documents/300608/files/daul_dbs.pdf eng info:eu-repo/semantics/altIdentifier/doi/10.1021/jp0731912 info:eu-repo/semantics/openAccess License undefined The Journal of Physical Chemistry A. - 2007, vol. 111, no. 37, p. 9145 -9163 info:eu-repo/classification/udc/54 DFT-based studies on the Jahn-Teller effect in 3D hexacyanometalates with orbitally degenerate ground states http://purl.org/coar/resource_type/c_6501