scholarly journals Ab Initio Non-Covalent Crystal Field Theory for Lanthanide Complexes: A Multiconfigurational Non-Orthogonal Group Functions Approach

2020 ◽  
Author(s):  
Alessandro Soncini ◽  
MATTEO PICCARDO
Keyword(s):  
Magnetic Properties ◽  
Perturbation Theory ◽  
Ab Initio ◽  
Crystal Field ◽  
Orthogonal Group ◽  
Lanthanide Complexes ◽  
Field Energy ◽  
First Order ◽  
Group Functions ◽  
Metal Ligand

We present a non-orthogonal fragment ab initio methodology for the calculation of crystal field energy levels and magnetic properties in lanthanide complexes, implementing a systematic description of non-covalent contributions to metal-ligand bonding. The approach has two steps. In the first step, appropriate ab initio wavefunctions for the various ionic fragments (lanthanide ion and coordinating ligands) are separately optimized, accounting for the electrostatic influence of the surrounding environment, within various approximations. In the second and final step, the scalar relativistic (DKH2) electrostatic Hamiltonian of the whole molecule is represented on the basis of the optimized metal-ligand multiconfigurational non-orthogonal group functions (MC-NOGF), and reduced to an effective (2J+1)-dimensional non-orthogonal Configuration Interaction (CI) problem via L{\"o}wdin-partitioning. Within the proposed formalism, the projected Hamiltonian can be implemented to any desired order of perturbation theory in the fragment-localised excitations out of the degenerate space, and its eigenvalues and eigenfunctions are systematic approximations to the crystal field energies and wavefunctions. We present a preliminary implementation of the proposed MC-NOGF method to first-order degenerate perturbation theory within our own ab initio code CERES, and compare its performance both with the simpler non-covalent orthogonal ab initio approach Fragment Ab Initio Model Potential (FAIMP) approximation, and with the full CAHF/CASCI-SO method, accounting for metal-ligand covalency in a mean-field manner. We find that energies and magnetic properties for 44 complexes obtained via an iteratively optimized version of our MC-NOGF first-order non-covalent method, compare remarkably well to the full CAHF/CASCI-SO method including metal-ligand covalency, and are superior to the best purely electrostatic results achieved via an iteratively optimized version of the FAIMP approach.<br>

scholarly journals Ab Initio Non-Covalent Crystal Field Theory for Lanthanide Complexes: A Multiconfigurational Non-Orthogonal Group Functions Approach

2020 ◽  
Author(s):  
Alessandro Soncini ◽  
MATTEO PICCARDO
Keyword(s):  
Magnetic Properties ◽  
Perturbation Theory ◽  
Ab Initio ◽  
Crystal Field ◽  
Orthogonal Group ◽  
Lanthanide Complexes ◽  
Field Energy ◽  
First Order ◽  
Group Functions ◽  
Metal Ligand

We present a non-orthogonal fragment ab initio methodology for the calculation of crystal field energy levels and magnetic properties in lanthanide complexes, implementing a systematic description of non-covalent contributions to metal-ligand bonding. The approach has two steps. In the first step, appropriate ab initio wavefunctions for the various ionic fragments (lanthanide ion and coordinating ligands) are separately optimized, accounting for the electrostatic influence of the surrounding environment, within various approximations. In the second and final step, the scalar relativistic (DKH2) electrostatic Hamiltonian of the whole molecule is represented on the basis of the optimized metal-ligand multiconfigurational non-orthogonal group functions (MC-NOGF), and reduced to an effective (2J+1)-dimensional non-orthogonal Configuration Interaction (CI) problem via L{\"o}wdin-partitioning. Within the proposed formalism, the projected Hamiltonian can be implemented to any desired order of perturbation theory in the fragment-localised excitations out of the degenerate space, and its eigenvalues and eigenfunctions are systematic approximations to the crystal field energies and wavefunctions. We present a preliminary implementation of the proposed MC-NOGF method to first-order degenerate perturbation theory within our own ab initio code CERES, and compare its performance both with the simpler non-covalent orthogonal ab initio approach Fragment Ab Initio Model Potential (FAIMP) approximation, and with the full CAHF/CASCI-SO method, accounting for metal-ligand covalency in a mean-field manner. We find that energies and magnetic properties for 44 complexes obtained via an iteratively optimized version of our MC-NOGF first-order non-covalent method, compare remarkably well to the full CAHF/CASCI-SO method including metal-ligand covalency, and are superior to the best purely electrostatic results achieved via an iteratively optimized version of the FAIMP approach.<br>

scholarly journals Configuration-averaged 4f orbitals in ab initio calculations of low-lying crystal field levels in lanthanide(iii) complexes

2016 ◽  
Vol 18 (23) ◽  
pp. 15807-15814 ◽  
Author(s):  
Willem Van den Heuvel ◽  
Simone Calvello ◽  
Alessandro Soncini
Keyword(s):  
Magnetic Properties ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Crystal Field ◽  
Lanthanide Complexes

We propose an ab initio method that simplifies the CASSCF/RASSI–SO approach for crystal field levels and magnetic properties of lanthanide complexes.

Magnetic properties of the mixed spin-5/2 and spin-3/2 Blume-Capel Ising system on the two-fold Cayley tree

Open Physics ◽  
2009 ◽  
Vol 7 (3) ◽  
Author(s):  
Rachidi Yessoufou ◽  
Saliou Amoussa ◽  
Felix Hontinfinde
Keyword(s):  
Magnetic Properties ◽  
Phase Transitions ◽  
Crystal Field ◽  
Cayley Tree ◽  
Second Order ◽  
Coordination Numbers ◽  
First Order ◽  
Mixed Spin ◽  
Second Order Transition ◽  
Zero Values

AbstractWe use exact recursion relations to study the magnetic properties of the half-integer mixed spin-5/2 and spin-3/2 Blume-Capel Ising ferromagnetic system on the two-fold Cayley tree that consists of two sublattices A and B. Two positive crystal-field interactions Δ1 and Δ2 are considered for the sublattice with spin-5/2 and spin-3/2 respectively. For different coordination numbers q of the Cayley tree sites, the phase diagrams of the model are presented with a special emphasis on the case q = 3, since other values of q reproduce similar results. First, the T = 0 phase diagram is illustrated in the (D A = Δ1/J,D B = Δ2/J) plane of reduced crystal-field interactions. This diagram shows triple points and coexistence lines between thermodynamically stable phases. Secondly, the thermal variation of the magnetization belonging to each sublattice for some coordination numbers q are investigated as well as the Helmoltz free energy of the system. First-order and second-order phase transitions are found. The second-order phase transitions become sharper and sharper when D A or D B increases. The first-order transitions only exist for some appropriate non-zero values of D A and/or D B. The corresponding transition lines never connect to the second-order transition lines. Thus, the non-existence of tricritical points remains one of the key features of the present model. The magnetic exponent β 0 of the model is estimated and found to be ¼ at small values of D A = D B = D and β 0 = ½ at large values of D. At intermediate values of D, there is a crossover region where the magnetic exponent displays interesting behaviours.

Magnetic properties of the seven-coordinated nanoporous framework material Co(bpy)1.5(NO3)2 (bpy = 4,4′-bipyridine)

2012 ◽  
Vol 41 (34) ◽  
pp. 10382-10389 ◽  
Author(s):  
Elena Bartolomé ◽  
Pablo Javier Alonso ◽  
Ana Arauzo ◽  
Javier Luzón ◽  
Juan Bartolomé ◽  
...  
Keyword(s):  
Heat Capacity ◽  
Magnetic Properties ◽  
Ab Initio ◽  
Crystal Field ◽  
Symmetry Axis ◽  
Squid Magnetometry ◽  
Induced Anisotropy ◽  
Large Crystal ◽  
Heat Capacity Measurements

The hepta-coordinated Co(bpy)1.5(NO3)2 molecule exhibits a large crystal field induced anisotropy along its binary symmetry axis, as deduced from SQUID magnetometry, EPR, heat capacity measurements and ab initio simulations.

Modeling the electronic states and magnetic properties derived from the f1 configuration in lanthanocene and actinocene compounds

2017 ◽  
Vol 46 (14) ◽  
pp. 4834-4843 ◽  
Author(s):  
Eduardo Solis-Céspedes ◽  
Dayán Páez-Hernández
Keyword(s):  
Magnetic Properties ◽  
Electronic Structure ◽  
Ab Initio ◽  
Crystal Field ◽  
Axial Symmetry ◽  
Electronic States ◽  
Theoretical Methods ◽  
Wavefunction Methods

The electronic structure and magnetic properties of a series of Kramers ions with f1 configuration in axial symmetry have been analyzed with a combination of theoretical methods: ab initio relativistic wavefunction methods as well as a crystal-field (CF) model with parameters extracted from the ab initio calculations.

Fast and reliable ab initio calculation of crystal field splittings in lanthanide complexes

2017 ◽  
Vol 147 (16) ◽  
pp. 164101 ◽  
Author(s):  
P. P. Hallmen ◽  
C. Köppl ◽  
G. Rauhut ◽  
H. Stoll ◽  
J. van Slageren
Keyword(s):  
Ab Initio ◽  
Crystal Field ◽  
Ab Initio Calculation ◽  
Lanthanide Complexes

scholarly journals Luminescence, Chiroptical, Magnetic and Ab-Initio Crystal-Field Characterizations of an Enantiopure Helicoidal Yb(III) Complex: The Van Vleck Rennaissance

2020 ◽  
Author(s):  
Frédéric Gendron ◽  
Sebastiano Di Pietro ◽  
Laura Abad Galan ◽  
François Riobé ◽  
Virginie Placide ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Electronic Structure ◽  
High Resolution ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Crystal Field ◽  
Chiroptical Properties ◽  
Spectroscopic Measurements ◽  
Combined Use ◽  
Van Vleck

<p>The electronic structure of a chiral Yb(III)-based complex is fully determined by taking advantage of experimental magnetic, luminescence, and chiroptical characterizations in combination with ab-initio wavefunction calculations. The combined use of these techniques allows determining with high resolution the electronic structure diagram as well as the nature of the different states involved in the magnetic and chiroptical properties of the investigated complex. The different crystal-field pictures deduced from spectroscopic measurements are re-conciliated in light of the magnetic properties and ab-initio results in the frame of the van Vleck initial vision. Advanced ab-initio calculations demonstrate that global chiroptical spectra correspond to the sum of intricated transitions with similar or opposite polarizations.</p>

scholarly journals Iron doped gold cluster nanomagnets: ab initio determination of barriers for demagnetization

2019 ◽  
Vol 1 (4) ◽  
pp. 1553-1559
Author(s):  
Christopher Ehlert ◽  
Ian P. Hamilton
Keyword(s):  
Magnetic Properties ◽  
Perturbation Theory ◽  
Ab Initio ◽  
Gold Cluster ◽  
Gold Clusters ◽  
Second Order ◽  
Multireference Perturbation Theory ◽  
Iron Doped

Magnetic properties of small- and nano-sized iron doped gold clusters are calculated at the level of second order multireference perturbation theory.

scholarly journals Luminescence, Chiroptical, Magnetic and Ab-Initio Crystal-Field Characterizations of an Enantiopure Helicoidal Yb(III) Complex: The Van Vleck Rennaissance

2020 ◽  
Author(s):  
Frédéric Gendron ◽  
Sebastiano Di Pietro ◽  
Laura Abad Galan ◽  
François Riobé ◽  
Virginie Placide ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Electronic Structure ◽  
High Resolution ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Crystal Field ◽  
Chiroptical Properties ◽  
Spectroscopic Measurements ◽  
Combined Use ◽  
Van Vleck

<p>The electronic structure of a chiral Yb(III)-based complex is fully determined by taking advantage of experimental magnetic, luminescence, and chiroptical characterizations in combination with ab-initio wavefunction calculations. The combined use of these techniques allows determining with high resolution the electronic structure diagram as well as the nature of the different states involved in the magnetic and chiroptical properties of the investigated complex. The different crystal-field pictures deduced from spectroscopic measurements are re-conciliated in light of the magnetic properties and ab-initio results in the frame of the van Vleck initial vision. Advanced ab-initio calculations demonstrate that global chiroptical spectra correspond to the sum of intricated transitions with similar or opposite polarizations.</p>

Sign in / Sign up

Export Citation Format

Share Document