A First-Principles Approach to the Calculation of the on-Site Zero-Field Splitting in Polynuclear Transition Metal Complexes

2014 ◽  
Vol 53 (21) ◽  
pp. 11785-11793 ◽  
Author(s):  
Marius Retegan ◽  
Nicholas Cox ◽  
Dimitrios A. Pantazis ◽  
Frank Neese
Keyword(s):  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
First Principles ◽  
Zero Field ◽  
Zero Field Splitting ◽  
Field Splitting

scholarly journals Spin–Phonon Coupling and Dynamic Zero-Field Splitting Contributions to Spin Conversion Processes in Iron(II) Complexes

2020 ◽  
Author(s):  
Nicholas Higdon ◽  
Alexandra Barth ◽  
Patryk Kozlowski ◽  
Ryan Hadt
Keyword(s):  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Single Molecule ◽  
Ligand Field ◽  
Zero Field ◽  
Phonon Coupling ◽  
Zero Field Splitting ◽  
Spin Conversion ◽  
Coupling Terms

Magnetization dynamics of transition metal complexes manifest in properties and phenomena of fundamental and applied interest (e.g., slow magnetic relaxation in single molecule magnets (SMMs), quantum coherence in quantum bits (qubits), and intersystem crossing (ISC) rates in photophysics). While spin–phonon coupling is recognized as an important determinant of these dynamics, additional fundamental studies are required to unravel the nature of the coupling and thus leverage it in molecular engineering approaches. To this end, we describe here a combined ligand field theory and multireference <i>ab initio</i> model to define spin–phonon coupling terms in S = 2 transition metal complexes and demonstrate how couplings originate from both the static and dynamic properties of ground and excited states. By extending concepts to spin conversion processes, ligand field dynamics manifest in the evolution of the excited state origins of zero-field splitting (ZFS) along specific normal mode potential energy surfaces. Dynamic ZFSs provide a powerful means to independently evaluate contributions from spin-allowed and/or -forbidden excited states to spin–phonon coupling terms. Furthermore, ratios between various intramolecular coupling terms for a given mode drive spin conversion processes in transition metal complexes and can be used to analyze mechanisms of ISC. Variations in geometric structure strongly influence the relative intramolecular linear spin–phonon coupling terms and will thus define the overall spin state dynamics. While of general importance for understanding magnetization dynamics, this study links the phenomenon of spin–phonon coupling across fields of single molecule magnetism, quantum materials/qubits, and transition metal photophysics.

scholarly journals Spin–Phonon Coupling and Dynamic Zero-Field Splitting Contributions to Spin Conversion Processes in Iron(II) Complexes

2020 ◽  
Author(s):  
Nicholas Higdon ◽  
Alexandra Barth ◽  
Patryk Kozlowski ◽  
Ryan Hadt
Keyword(s):  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Single Molecule ◽  
Ligand Field ◽  
Zero Field ◽  
Phonon Coupling ◽  
Zero Field Splitting ◽  
Spin Conversion ◽  
Coupling Terms

Magnetization dynamics of transition metal complexes manifest in properties and phenomena of fundamental and applied interest (e.g., slow magnetic relaxation in single molecule magnets (SMMs), quantum coherence in quantum bits (qubits), and intersystem crossing (ISC) rates in photophysics). While spin–phonon coupling is recognized as an important determinant of these dynamics, additional fundamental studies are required to unravel the nature of the coupling and thus leverage it in molecular engineering approaches. To this end, we describe here a combined ligand field theory and multireference <i>ab initio</i> model to define spin–phonon coupling terms in S = 2 transition metal complexes and demonstrate how couplings originate from both the static and dynamic properties of ground and excited states. By extending concepts to spin conversion processes, ligand field dynamics manifest in the evolution of the excited state origins of zero-field splitting (ZFS) along specific normal mode potential energy surfaces. Dynamic ZFSs provide a powerful means to independently evaluate contributions from spin-allowed and/or -forbidden excited states to spin–phonon coupling terms. Furthermore, ratios between various intramolecular coupling terms for a given mode drive spin conversion processes in transition metal complexes and can be used to analyze mechanisms of ISC. Variations in geometric structure strongly influence the relative intramolecular linear spin–phonon coupling terms and will thus define the overall spin state dynamics. While of general importance for understanding magnetization dynamics, this study links the phenomenon of spin–phonon coupling across fields of single molecule magnetism, quantum materials/qubits, and transition metal photophysics.

Accurate thermochemistry for transition metal complexes from first-principles calculations

2009 ◽  
Vol 131 (2) ◽  
pp. 024106 ◽  
Author(s):  
Nathan J. DeYonker ◽  
T. Gavin Williams ◽  
Adam E. Imel ◽  
Thomas R. Cundari ◽  
Angela K. Wilson
Keyword(s):  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
First Principles ◽  
First Principles Calculations

scholarly journals From Positive to Negative Zero-Field Splitting in a Series of Strongly Magnetically Anisotropic Mononuclear Metal Complexes

2017 ◽  
Vol 56 (24) ◽  
pp. 14809-14822 ◽  
Author(s):  
Ghénadie Novitchi ◽  
Shangda Jiang ◽  
Sergiu Shova ◽  
Fatima Rida ◽  
Ivo Hlavička ◽  
...  
Keyword(s):  
Metal Complexes ◽  
Zero Field ◽  
Zero Field Splitting ◽  
Field Splitting

scholarly journals First-Principles Investigations of Magnetic Anisotropy and Spin-Crossover Behavior of Fe(III)-TBP Complexes

2020 ◽  
Author(s):  
Rishu Khurana ◽  
Sameer Gupta ◽  
Md. Ehesan Ali
Keyword(s):  
Single Molecule ◽  
First Principles ◽  
Density Functional ◽  
Spin Crossover ◽  
Zero Field ◽  
Spin States ◽  
Zero Field Splitting ◽  
Field Splitting ◽  
B3lyp Functional ◽  
D Values

<div>With the ongoing efforts to obtain mononuclear 3d-transition metal complexes that manifest slow relaxation of magnetization and hence, can behave as single molecule magnets (SMMs), we have modelled 14 novel Fe(III) complexes out of which nine behave as potential SMMs. These complexes possess large zero-field splitting (ZFS)</div><div>parameter D in the range of -40 to -60 cm<sup>-1</sup>. The first-principles investigation of the ground-spin state applying density functional theory (DFT) and wave-function based</div><div>multi-configurations methods e.g. SA-CASSCF/NEVPT2 are found to be quite consistent except for few delicate cases with near degenerate spin-states. In such cases, the</div><div>hybrid B3LYP functional is found to be biased towards high-spin (HS) state. Altering the percentage of exact exchange admixed in B3LYP functional leads to intermediate spin</div><div>(IS) ground state consistent with the multireference calculations. The origin of large zero field splitting (ZFS) in the Fe(III)-based trigonal bipyramidal (TBP) complexes</div><div>is investigated and the D-values are further tuned by varying the axial ligands with group XV elements (N, P and As) and equatorial halide ligands from F, Cl, Br and I. Furthermore, a number of complexes are identified with very small Gibbs free energy values indicating the possible spin-crossover phenomenon between the bi-stable spin-states.</div>

Electron and nuclear spin relaxation in paramagnetic transition-metal complexes with S = 1. The effects of a non-zero average zero-field splitting on the spin energy levels

1978 ◽  
Vol 31 (3) ◽  
pp. 475 ◽  
Author(s):  
DT Pegg ◽  
DM Doddrell
Keyword(s):  
Transition Metal Complexes ◽  
Spin Relaxation ◽  
Energy Levels ◽  
Nuclear Spin Relaxation ◽  
Zero Field ◽  
Zero Field Splitting ◽  
Field Splitting ◽  
Electron Spin Relaxation ◽  
Spin Lattice ◽  
Splitting Constant

The effects of a non-zero average zero-field splitting on electron spin relaxation in paramagnetic (S = 1) complexes is treated theoretically. The spin-lattice interaction is postulated to be a simple scalar P(t). S process with correlation time Ti. This process is assumed not to modulate the zero-field splitting which, however, is modulated by the molecular tumbling. The frequency dependence of the nuclear relaxation time (Tl) now depends on the magnitude of the zero-field splitting constant (D), and, for large values of D, the value of T1 is independent of the applied field strength.

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