Ligand Field Interaction Research Articles

Relation between Electrostatic Charge Density and Spin Hamiltonian Models of Ligand Field in Lanthanide Complexes.

Understanding the ligand field interactions in lanthanide-containing magnetic molecular complexes is of paramount importance for understanding their magnetic properties, and simple models for rationalizing their effects are much desired. In this work, the equivalence between electrostatic models, which derive their results from calculating the electrostatic interaction energy of the charge density of the 4f electrons in an electrostatic potential representing the ligands, and the common quantum mechanical effective spin Hamiltonian in the space of the ground J multiplet is formulated in detail. This enables the construction of an electrostatic potential for any given ligand field Hamiltonian and discusses the effects of the ligand field interactions in terms of an interaction of a generalized 4f charge density with the electrostatic potential. Such models often allow for an easier rationalization of the ligand field interactions, and it can be hoped that the results in this work will help us to better understand the effects of ligand field in lanthanide complexes.

Characterizing Excited States of a Copper-Based Molecular Qubit Candidate with Correlated Electronic Structure Methods.

Molecular spins have a variety of potential advantages as qubits for quantum computation, such as tunability and well-understood design pathways through organometallic synthesis. Organometallic and heavy-metal-based molecular spin qubits can also exhibit rich electronic structures due to ligand field interactions and electron correlation. These features make consistent and reliable modeling of these species a considerable challenge for contemporary electronic structure techniques. Here, we elucidate the electronic structure of a Cu(II) complex analogous to a recently proposed room-temperature molecular spin qubit. Using active space methods to describe the electron correlation, we show the nuanced interaction between the metal d orbitals and ligand σ and π orbitals makes these systems challenging to model, both in terms of the delocalized spin density and the excited state ordering. We show that predicting the correct spin delocalization requires special consideration of the Cu d orbitals and that the excited state spectrum for the Cu(III) complex also requires the explicit inclusion of the π orbitals in the active space. These interactions are rather common in molecular spin qubit motifs and may play an important role in spin-decoherence processes. Our results may lend insight into future studies of the orbital interactions and electron delocalization of similar complexes.

Photoluminescent Lanthanide(III) Coordination Polymers with Bis(1,2,4-Triazol-1-yl)Methane Linker

A series of new lanthanide(III) coordination polymers with the general formula [Ln(btrm)2(NO3)3]n, where btrm = bis(1,2,4-triazol-1-yl)methane and Ln = Eu3+, Tb3+, Sm3+, Dy3+, Gd3+ were synthesized and characterized by IR-spectroscopy, elemental, thermogravimetric, single-crystal, and powder X-ray diffraction analyses. Europium(III), samarium(III), terbium(III), and gadolinium(III) coordination polymers demonstrate thermal stability up to 250 °C, while dysprosium(III) is stable up to 275 °C. According to single-crystal X-ray diffraction analysis, the ligand exhibits a bidentate-bridging coordination mode, forming a polymeric chain of octagonal metallocycles. The photoluminescence of the free ligand in the polycrystalline state is observed in the ultraviolet range with a quantum yield of 13%. The energy transfer from the ligand to the lanthanide ions was not observed for all obtained coordination polymers. However, there are sharp bands of lanthanide(III) ions in the diffuse reflectance and excitation spectra of the obtained compounds. Therefore, Ln(III) luminescence arises, most probably, from the enhancement of f-f transition intensity under the influence of the ligand field and non-centrosymmetric interactions.

Ab Initio Investigation of the Na3[Ln(ODA)3]·2NaClO4·6H2O (Ln = Ce-Yb; ODA = Oxydiacetate) Series.

In this work, the Na3[Ln(ODA)3]·2NaClO4·6H2O (Ln = Ce-Yb; ODA = oxydiacetate) series was analyzed with the ab initio ligand field theory (AILFT) module of the ORCA computational suite. The results were discussed within the framework of the angular overlap model (AOM) and compared to literature data. We find that the structural changes observed across the series exemplifies the effects of the lanthanide contraction also manifesting in the value of the AOM parameters. It is also shown that the complete active space self-consistent field (CASSCF) methodology is sufficient to describe the ligand field interactions in mononuclear lanthanide complexes, and the effects of dynamic correlation, through n-electron valence state perturbation theory (NEVPT2), are discussed. The calculated ligand field parameters of the present work are compared to the experimentally derived values from the literature.

Regulating Surface Reaction Kinetics through Ligand Field Effects for Fast and Reversible Aqueous Zinc Batteries

AbstractDesigning water‐deficient solvation sheath of Zn2+ by ligand substitution is a widely used strategy to protect Zn metal anode, yet the intrinsic tradeoff between Zn nucleation/dissolution kinetics and the side hydrogen evolution reaction (HER) remains a huge challenge. Herein, we find boric acid (BA) with moderate ligand field interaction can partially replace H2O molecules in the solvation sheath of Zn2+, forming a stable water‐deficient solvation sheath. It enables fast Zn nucleation/dissolution kinetics and substantially suppressed HER. Crucially, by systematically comparing the ligand field strength and solvation energies between BA and the ever‐reported electrolyte additives, we also find that the solvation energy has a strong correlation with Zn nucleation/dissolution kinetics and HER inhibition ability, displaying a classic volcano behavior. The modulation map could provide valuable insights for solvation sheath design of zinc batteries and beyond.

Regulating Surface Reaction Kinetics through Ligand Field Effects for Fast and Reversible Aqueous Zinc Batteries.

Designing water-deficient solvation sheath of Zn2+ by ligand substitution is a widely used strategy to protect Zn metal anode, yet the intrinsic tradeoff between Zn nucleation/dissolution kinetics and the side hydrogen evolution reaction (HER) remains a huge challenge. Herein, we find boric acid (BA) with moderate ligand field interaction can partially replace H2 O molecules in the solvation sheath of Zn2+ , forming a stable water-deficient solvation sheath. It enables fast Zn nucleation/dissolution kinetics and substantially suppressed HER. Crucially, by systematically comparing the ligand field strength and solvation energies between BA and the ever-reported electrolyte additives, we also find that the solvation energy has a strong correlation with Zn nucleation/dissolution kinetics and HER inhibition ability, displaying a classic volcano behavior. The modulation map could provide valuable insights for solvation sheath design of zinc batteries and beyond.

LFDFT—A Practical Tool for Coordination Chemistry

The electronic structure of coordination compounds with lanthanide ions is studied by means of density functional theory (DFT) calculations. This work deals with the electronic structure and properties of open-shell systems based on the calculation of multiplet structure and ligand-field interaction, within the framework of the Ligand–Field Density-Functional Theory (LFDFT) method. Using effective Hamiltonian in conjunction with the DFT, we are able to reasonably calculate the low-lying excited states of the molecular [Eu(NO3)3(phenanthroline)2] complex, subjected to the Eu3+ configuration 4f6. The results are compared with available experimental data, revealing relative uncertainties of less than 5% for many energy levels. We also demonstrate the ability of the LFDFT method to simulate absorption spectrum, considering cerocene as an example. Ce M4,5 X-ray absorption spectra are simulated for the complexes [Ce(η8−C8H8)2] and [Ce(η8−C8H8)2][Li(tetrahydrofurane)4], which are approximated by the Ce oxidation states 4+ and 3+, respectively. The results showed a very good agreement with the experimental data for the Ce3+ compound, unlike for the Ce4+ one, where charge transfer electronic structure is still missing in the theoretical model. Therefore this presentation reports the benefits of having a theoretical method that is primarily dedicated to coordination chemistry, but it also outlines limitations and places the ongoing developmental efforts in the broader context of treating complex molecular systems.

Resonant X-ray photo-oxidation of light-harvesting iron (II/III) N-heterocyclic carbene complexes

Two photoactive iron N-heterocyclic carbene complexes {[hbox {Fe}^{{{rm{II}}}}(hbox {btz})_2(hbox {bpy})]^{2+}} and {[hbox {Fe}^{{rm{III}}}(hbox {btz})_3]^{3+}}, where btz is 3,3’-dimethyl-1,1’-bis(p-tolyl)-4,4’-bis(1,2,3-triazol-5-ylidene) and bpy is 2,2’-bipyridine, have been investigated by Resonant Photoelectron Spectroscopy (RPES). Tuning the incident X-ray photon energy to match core-valence excitations provides a site specific probe of the electronic structure properties and ligand-field interactions, as well as information about the resonantly photo-oxidised final states. Comparing measurements of the Fe centre and the surrounding ligands demonstrate strong mixing of the Fe {hbox {t}_{{rm{2g}}}} levels with occupied ligand pi orbitals but weak mixing with the corresponding unoccupied ligand orbitals. This highlights the importance of pi-accepting and -donating considerations in ligand design strategies for photofunctional iron carbene complexes. Spin-propensity is also observed as a final-state effect in the RPES measurements of the open-shell hbox {Fe}^{{rm{III}}} complex. Vibronic coupling is evident in both complexes, where the energy dispersion hints at a vibrationally hot final state. The results demonstrate the significant impact of the iron oxidation state on the frontier electronic structure and highlights the differences between the emerging class of hbox {Fe}^{{rm{III}}} photosensitizers from those of more traditional hbox {Fe}^{{rm{II}}} complexes.

Ab initio based ligand field approach to determine electronic multiplet properties

A method is developed to calculate the ligand field (LF) parameters and the multiplet spectra of local magnetic centers with open $d$ and $f$ shells in solids in a parameter-free way. This method proceeds from density functional theory and employs Wannier projections of nonmagnetic band structures onto local $d$ or $f$ orbitals. Energies of multiplets and optical, as well as x-ray spectra are determined by exact numerical diagonalization of a local Hamiltonian describing Coulomb, LF, and spin-orbit interactions. The method is tested for several $3d$ and $5f$ compounds for which the LF parameters and multiplet spectra are experimentally well known. In this way, we obtain good agreement with the experiments for ${\mathrm{La}}_{2}{\mathrm{NiO}}_{4}, {\mathrm{CaCuO}}_{2}, {\mathrm{Li}}_{2}{\mathrm{CuO}}_{2}$, ZnO:Co, and ${\mathrm{UO}}_{2}$.

150 KeV Cu− ion- implantation in SrVO3 thin films: A study of Cu induced defect states

Investigations on the extrinsic defects induced alteration in B–O6 octahedra, energy band-structure amendments and physical assets of ABO3 perovskites are technologically important and require modest approaches for the defect creation and their investigations. In this study, Cu defects have been assimilated in SrVO3 films using 150 KeV Cu ion-implantation with two different ion fluences; 1.63 × 1015 ion/cm2 and 8.15 × 1015 ion/cm2. The implanted Cu ions do not make metallic/oxide clusters in SrVO3 films, as confirmed by XRD studies, but have facilitated the lattice parameter enlargement and energy band-gap narrowing by creating their defect states and V–O6 octahedra distortion. NEXAFS spectra at Cu L-edge have confirmed the Cu2+ ions in low/high Cu doses implanted SrVO3 films. Cu defects induced V–O6 octahedra distortion has manifested a diverse ligand field interaction between V 3 d and O 2p orbitals and has narrowed the; (i) energy gap of V 2p3/2 and V 2p1/2 transitions and (ii) energy gap between t2g/eg and the O 2p and metal (n+1)sp hybridized orbitals, leading to the band-structure alteration of SrVO3 films. Mechanistic understanding of band-structure perturbation is discussed in the light of ion-solid interaction induced defect formation in SrVO3 thin films.

Electronic Structure and Photoluminescence Properties of Eu(η9-C9H9)2.

The electronic structure of Eu2+ compounds results from a complex combination of strongly correlated electrons and relativistic effects as well as weak ligand-field interaction. There is tremendous interest in calculating the electronic structure as nowadays the Eu2+ ion is becoming more and more crucial, for instance, in lighting technologies. Recently, interest in semiempirical methods to qualitatively evaluate the electronic structure and to model the optical spectra has gained popularity, although the theoretical methods strongly rely upon empirical inputs, hindering their prediction capabilities. Besides, ab initio multireference models are computationally heavy and demand very elaborative theoretical background. Herein, application of the ligand-field density functional theory (LFDFT) method that is recently available in the Amsterdam Modeling Suite is shown: (i) to elucidate the electronic structure properties on the basis of the multiplet energy levels of Eu configurations 4f7 and 4f65d1 and (ii) to model the optical spectra quite accurately if compared to the conventional time-dependent density functional theory tool. We present a theoretical study of the molecular Eu(η9-C9H9)2 complex and its underlying photoluminescence properties with respect to the Eu 4f-5d electron transitions. We model the excitation and emission spectra with good agreement with the experiments, opening up the possibility of modeling lanthanides in complex environment like nanomaterials by means of LFDFT at much-reduced computational resources and cost.

The role of the quadrupolar interaction in the tunneling dynamics of lanthanide molecular magnets

Quantum tunneling dominates the low temperature magnetization dynamics in molecular magnets and presents features that are strongly system dependent. The current discussion is focused on the terbium(III) bis(phtalocyanine) ([TbPc2]−1) complex that should serve as a prototypical case for lanthanide molecular magnets. We analyze numerically the effect of non-axial interactions on the magnitude of the intrinsic tunnel splitting and show that usual suspects like the transverse ligand field and Zeeman interaction fail to explain the experimentally observed dynamics. We then propose through the nuclear quadrupolar interaction a viable mechanism that mixes, otherwise almost degenerate hyperfine states.

Mechanistic insights on the electronic properties and electronic/atomic structure aspects in orthorhombic SrVO3 thin films: XANES-EXAFS study.

Correlations among the B-O6 octahedra distortions, existing polymorphous phases, band structures and electronic conductivities of ABO3 perovskites are matters for debate and require a deep understanding of their local atomic/electronic structures and diverse assets. In this study, to illustrate the distortion in V-O6 octahedra and its implication on the band structure and electronic properties, spectroscopic investigations on the RF-sputtering grown insulating SrVO3 thin films were employed using X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS). V K-edge and V L3,2-edge XANES, along with atomic multiplet calculations, have confirmed the 4+ oxidation state of V ions in the pristine and annealed SrVO3 thin films. Lower t2g/eg peak intensity ratio and smaller energy separation between t2g and eg peaks in the O K-edge XANES spectra, compared to the VO2 reference sample, have confirmed a larger V-O6 distortion in the orthorhombic SrVO3 thin films. Moreover, from the EXAFS data analysis, the local orthorhombic structure has been identified in the pristine and annealed SrVO3 thin films, compelling significant distortion in the V-O6 octahedra. Dimerization in the vanadium chains and V-V twisting, caused by V-O6 octahedra distortion, manifests a miscellaneous ligand field interaction between O 2p and V 3d orbitals and facilitates (i) a larger separation between the bonding and antibonding d‖ orbitals and (ii) an upward shift of the π* band in the band structure, leading to larger band gaps in the insulating SrVO3 thin films. Our spectroscopy results may open up new avenues for the mechanism of insulating/conducting character in other complicated perovskite materials using XANES-EXAFS.

The Ligand Fields Characterizations within Erbium-Tellurite Glass Network via Gold Nanoparticles Concentration Variation

Glass samples of composition 79TeO2 – 15PbO – 5PbCl2 – 1Er2O3 – (x)AuCl3 with (0.0 ≤ x ≤ 0.1 mol%) were successfully synthesized by using melt-quenching technique. The impacts of gold nanoparticles (GNPs) concentration in stimulating the ligand field interaction inside the erbium-tellurite glass network were inspected. Amorphous nature of the sample was confirmed through XRD pattern. TEM images display the existence of GNPs with average diameter ~1.24 nm. Optical absorption spectra were recorded in the UV-Visible range. The absorption displays several prominent peaks corresponding to the transitions from the ground state to the excited states of Er3+ ion. The compositional dependence of the ligand parameters in terms of crystal field strength and Racah parameter were determined.

Giant Magnetic Anisotropy of Co, Ru, and Os Adatoms on MgO (001) Surface.

Large magnetic anisotropy energy (MAE) is desirable and critical for nanoscale magnetic devices. Here, using ligand-field level diagrams and density functional calculations, we well explain the very recent discovery [I. G. Rau etal., Science 344, 988 (2014)] that an individual Co adatom on a MgO (001) surface has a large MAE of more than 60meV. More importantly, we predict that a giant MAE up to 110meV could be realized for Ru adatoms on MgO (001), and even more for the Os adatoms (208meV). This is a joint effect of the special ligand field, orbital multiplet, and significant spin-orbit interaction, in the intermediate-spin state of the Ru or Os adatoms on top of the surface oxygens. The giant MAE could provide a route to atomic scale memory.

Intracluster interactions in butterfly{Fe3LnO2}molecules with the non-Kramers ions Tb(III) and Ho(III)

The intracluster exchange interactions within the ``butterfly'' $[{\mathrm{Fe}}_{3}\mathrm{Ln}({\ensuremath{\mu}}_{3}\ensuremath{-}\mathrm{O}{)}_{2}({\mathrm{CCl}}_{3}\mathrm{COO}{)}_{8}({\mathrm{H}}_{2}\mathrm{O})(\mathrm{THF}{)}_{3}]$ molecules, where Ln(III) represents a lanthanide cation, have been determined by a combination of x-ray magnetic circular dichroism (XMCD) and vibrating sample magnetometry (VSM) along with an interaction model. We have studied the compounds with $\mathrm{Ln}=\mathrm{Tb}$ and Ho, both non-Kramers lanthanides and with high uniaxial anisotropy, and $\mathrm{Ln}=\mathrm{Lu}$(III) and Y(III) as pseudolanthanides, which supply nonmagnetic Ln reference cases. At low temperature, the three Fe atoms can be considered as a self-unit with total spin ${S}_{{\mathrm{Fe}}_{3}}=5/2$. Using the element selectivity of the XMCD magnetometry, measured at the Ln ${L}_{2,3}$ edges, together with the VSM measurements, the local magnetization of the Ln ion and the ${\mathrm{Fe}}_{3}$ subcluster, as a function of the field and low temperature ($T\ensuremath{\approx}2.5\phantom{\rule{0.28em}{0ex}}\mathrm{K}$), has been determined separately. These results are described quantitatively in the framework of a theoretical model based on an effective spin Hamiltonian, which considers the competing effects of intracluster interactions and the external applied magnetic field. The $\mathrm{Ln}\ensuremath{-}{\mathrm{Fe}}_{3}$ exchange interaction within the ${{\mathrm{Fe}}_{3}{\mathrm{LnO}}_{2}}$ cluster has been determined to be antiferromagnetic, in both Tb and Ho compounds, with ${\mathcal{J}}_{\mathrm{FeTb}}/{\mathrm{k}}_{\mathrm{B}}=\ensuremath{-}0.13(1)\phantom{\rule{0.28em}{0ex}}\mathrm{K}$ and ${\mathcal{J}}_{\mathrm{FeHo}}/{\mathrm{k}}_{\mathrm{B}}=\ensuremath{-}0.18(1)\phantom{\rule{0.28em}{0ex}}\mathrm{K}$, respectively. In both cases, a field-induced reorientation of the ${\mathrm{Fe}}_{3}$ and Ln spins from antiparallel to parallel orientation takes place at a threshold field ${\ensuremath{\mu}}_{0}H=1.1$ and 2 T, for the ${{\mathrm{Fe}}_{3}{\mathrm{TbO}}_{2}}$ and ${{\mathrm{Fe}}_{3}{\mathrm{HoO}}_{2}}$ compounds, respectively. By comparison with other compounds of the series with uniaxial anisotropy, it is concluded that the polarizability of the ${\mathrm{Fe}}_{3}$ subcluster magnetic moment decreases in the trend ${{\mathrm{Fe}}_{3}{\mathrm{YO}}_{2}}\phantom{\rule{0.28em}{0ex}}\ensuremath{\rightarrow}\phantom{\rule{0.28em}{0ex}}{{\mathrm{Fe}}_{3}{\mathrm{TbO}}_{2}}\phantom{\rule{0.28em}{0ex}}\ensuremath{\rightarrow}\phantom{\rule{0.28em}{0ex}}{{\mathrm{Fe}}_{3}{\mathrm{HoO}}_{2}}\phantom{\rule{0.28em}{0ex}}\ensuremath{\rightarrow}\phantom{\rule{0.28em}{0ex}}{{\mathrm{Fe}}_{3}{\mathrm{DyO}}_{2}}$, because of the increasing opposition of the exchange antiferromagnetic field caused by the Ln ion. In the $\mathrm{Ln}=\mathrm{Tb}$, Ho, and Dy, the magnetization of the whole molecule is dominated by the anisotropy of the Ln ion. The intracluster ${\mathrm{Fe}}_{3}\ensuremath{-}\mathrm{Ln}$ exchange interactions are very weak compared to the Ln ligand field and Fe-Fe exchange interactions.

EPR investigation of local structure for the [Mn(H2O)6]2+cluster in M(ClO4)2· 6H2O:Mn2+(M = Cd, Hg) systems at different temperatures

Local lattice structure distortion studies of the octahedral Mn 2+ center in M(ClO 4 ) 2 · 6H 2 O:Mn 2+ (M = Cd, Hg) systems have been performed systematically based on the diagonalization of the complete energy matrices of electron-electron repulsion, spin-orbit coupling and trigonal ligand-field interaction for a d 5 configuration ion in a trigonal ligand field. From the EPR calculation, the local structure distortion parameters R and θ are determined, respectively. Results show that the local lattice structure around a trigonal Mn 2+ center has a compressed distortion along the crystalline C 3 axis. The compression distortion may be ascribed to the fact that the radius of the Mn 2+ ion is smaller than that of the Hg 2+ ion and the Cd 2+ ion. The local lattice structure parameters for Mn 2+ in M(ClO 4 ) 2 · 6H 2 O:Mn 2+ (M = Cd, Hg) systems are determined at liquid-nitrogen temperature and room temperature.

Ligand field and intermolecular interactions tuning the magnetic properties of spin-crossover Fe(II) polymer with 4,4′-bipyridine

A new spin crossover coordination polymer (SCO-CPs) of Fe(II)-4,4′-bipyridine (4,4′-bipy) family: {Fe(4,4′-bipy)2(H2O)2}·(4,4′-bipy)· 8(H2O)·2(ClO4) (3), which displays half spin transitions between 100 and 300K, has been synthesized and structurally characterized. Compound 3 featured with two-dimensional (2-D) grids connected by hydrogen bonds and π…π packing between one-dimensional (1-D) chains, the 2-D grids expand to three-dimensional (3-D) architecture supported by a “S-shaped holder” involving lattice 4-4′-bipy, water molecules and perchlorate anion. We compared 3 with the other two analogous complexes: ({Fe(4,4′-bipy) (H2O)2 (NCS)2}·4,4′-bipy, 1 and {Fe(4,4′-bipy)2(NCS)2}·mSolv, 2) through Hirshfeld surfaces analysis, which revealed that the low ligand field strength (NCS−) and lone-pair…H contacts contribute to the stabilization of HS (high-spin) state of the Fe(II) ion, while the high ligand field strength (4,4′-bipy) and strong intermolecular contacts (hydrogen bonds and π…π packing interactions) make for the LS (low-spin) state.

How strongly are the magnetic anisotropy and coordination numbers correlated in lanthanide based molecular magnets?

Ab initio CASSCF + RASSI-SO investigations on a series of lanthanide complexes [LnIII = Dy(1), Tb(2), Ce(3), Nd(4), Pr(5) and Sm(6)] have been undertaken and in selected cases (for 1, 2, 3 and 4) coordination number (C.N.) around the LnIII ion has been gradually varied to ascertain the effect of C.N. on the magnetic anisotropy. Our calculations reveal that complex 3 possesses the highest barrier height for reorientation of magnetisation (Ueff) and predict that 3 is likely to exhibit Single Molecule Magnet (SMM) behaviour. Complex 5 on the other hand is predicted to preclude any SMM behaviour as there is no intrinsic barrier for reorientation of magnetization. Ground state anisotropy of all the complexes show mixed behaviour ranging from pure Ising type to fully rhombic behaviour. Coordination number around the lanthanide ion is found to alter the magnetic behaviour of all the lanthanide complexes studied and this is contrary to the general belief that the lanthanide ions are inert and exert small ligand field interaction. High symmetric low-coordinate LnIII complexes are found to yield large Ueff values and thus should be the natural targets for achieving very large blocking temperatures.

Theoretical investigations of optical spectra and electron paramagnetic resonance spectra of LiCl:Ni2+ crystals

The complete energy matrices (45×45) including low symmetry ligand field (C4v) and Coulomb interactions for 3d8 ions have been constructed, and the high-order perturbation formulas of spin-Hamiltonian (SH) parameters g factors g//, g⊥ and zero-field splitting (ZFS) parameter D for ground state 3A2g of the 3d8 ions in the tetragonal symmetry environment have been derived. In those formulas both the crystal field (CF) mechanism and the charge transfer (CT) mechanism are taken into account. The complete energy matrices and the high-order perturbation formulas are applied to calculate the energy levels and SH parameters of the Ni2+ ion in LiCl crystal respectively. The results are in reasonable agreement with the experimental data and indicate that CT mechanism plays important role in the understanding of SH parameters, especially the g factors. All the multiplet energy are assigned theoretically and the local structures of LiCl:Ni2+ are established.