Molecular orbital approach to the spectra of the Co2+ ion in tetrahedral crystals with axial distortion

1970 ◽  
Vol 48 (19) ◽  
pp. 2221-2230 ◽  
Author(s):  
S. Jugessur ◽  
J.-Y. Savard ◽  
R. Rai
Keyword(s):  
Fine Structure ◽  
Energy Levels ◽  
Basis Functions ◽  
Zero Field ◽  
Spin Orbit Coupling ◽  
Coupling Constant ◽  
Zero Field Splitting ◽  
Free Ion ◽  
Semi Empirical ◽  
Lcao Mo

The semi-empirical LCAO–MO method has been utilized to study the electronic spectra of the Co2+ ion embedded in host crystals of CdS, ZnS, and ZnO. The crystals are assumed to have an axial distortion, thereby changing the Td symmetry to C3v. One-electron energy levels and state vectors are evaluated by the MO method. The results are used to analyze the fine structure of the optical bands of the Co2+ ion in those environments, and to calculate the anisotropic [Formula: see text] and [Formula: see text] and the zero-field splitting D. It is found that the molecular orbitals are good basis functions and that the spin–orbit coupling constant λ, less than the free ion value, is required for a proper assignment of the fine-structure bands.

Correlation of Zero Field Splittings and Site Distortions V. Mn2+ in Cs2Zn3S4

1983 ◽  
Vol 38 (2) ◽  
pp. 149-153 ◽  
Author(s):  
M. Heming ◽  
G. Lehmann
Keyword(s):  
Fine Structure ◽  
Hyperfine Splitting ◽  
Site Symmetry ◽  
Zero Field ◽  
Structure Parameters ◽  
Zero Field Splitting ◽  
Zero Field Splitting Parameter ◽  
Free Ion ◽  
Splitting Parameter ◽  
Epr Signal

Abstract In platelets of Cs2Zn3S4 with about 4% of the Zn substituted by Mn two nonequivalent centers of isolated Mn2+ were observed in addition to a broad EPR signal near g = 2 which is assigned to clusters of interconnected MnS4 units. The fine structure and hyperfine structure parameters for the single-ion centers (all in units of 1CT 4 cm -1) areb02 = -318.3 ± 3; b22 = -210.3 ± 2; Ay = -62.7; Az = -63.6 ± 0.8;b02 = -890 ± 18; b22 = -743 ± 36; Ay = -60.6; Az = - 61.4 ± 0.8;for centers I and II, resp. Center II arises from Zn sites of C 2 site symmetry while for center I assignment to either one of two sites with D2 site symmetry is possible. The larger hyperfine splitting constants as well as the superposition analysis favor the larger sites which are not occupied by Zn, but are partly occupied in the analogous Mn (and Co) compounds. Superposition analysis yields the same value of + 0.12 ± 0.02 cm-1 for the intrinsic zero field splitting parameter b̄2 of the bridging MnS4 units in both sites. gz is significantly higher than the free ion value indicating a higher degree of covalency than in Cds and CdGa2S4.

Ground configuration splitting in UCl5

1977 ◽  
Vol 55 (10) ◽  
pp. 937-942 ◽  
Author(s):  
A. F. Leung ◽  
Ying-Ming Poon
Keyword(s):  
Crystal Field ◽  
Energy Levels ◽  
Orbit Coupling ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Coupling Constant ◽  
Point Charge Model ◽  
X Ray Crystallography ◽  
Charge Model ◽  
Crystal Field Parameters

The absorption spectra of UCl5 single crystal were observed in the region between 0.6 and 2.4 μm at room, 77, and 4.2 K temperatures. Five pure electronic transitions were assigned at 11 665, 9772, 8950, 6643, and 4300 cm−1. The energy levels associated with these transitions were identified as the splittings of the 5f1 ground configuration under the influence of the spin–orbit coupling and a crystal field of C2v symmetry. The number of crystal field parameters was reduced by assuming the point-charge model where the positions of the ions were determined by X-ray crystallography. Then, the crystal field parameters and the spin–orbit coupling constant were calculated to be [Formula: see text],[Formula: see text], [Formula: see text], and ξ = 1760 cm−1. The vibronic analysis showed that the 90, 200, and 320 cm−1 modes were similar to the T2u(v6), T1u(v4), and T1u(v3) of an UCl6− octahedron, respectively.

The EPR Zero-Field Splitting D and its Pressure and Temperature Dependence for Trigonal Mn2+ Centers in [Zn(H2O)6](BF4)2:Mn2+ Crystal

2006 ◽  
Vol 61 (5-6) ◽  
pp. 289-292 ◽  
Author(s):  
Hong-Gang Liu ◽  
Xiao-Xuan Wu ◽  
Wen-Chen Zheng ◽  
Lv He
Keyword(s):  
Temperature Dependence ◽  
Room Temperature ◽  
Coupling Mechanism ◽  
Zero Field ◽  
Spin Orbit Coupling ◽  
Zero Field Splitting ◽  
Field Splitting ◽  
Thermal Expansion Coefficients ◽  
Perturbation Formula ◽  
Expansion Coefficients

The EPR zero-field splitting D (= b02 ) and its pressure and temperature dependence for trigonal Mn2+ centers in low and room temperature phases in [Zn(H2O)6](BF4)2 :Mn2+ crystal are studied by a high-order perturbation formula based on the dominant spin-orbit coupling mechanism. From the studies, the local trigonal distortion angles, the local angular compressibilities and the local angular thermal expansion coefficients for Mn2+ centers in both phases of the [Zn(H2O)6](BF4)2 crystal are estimated. The results are discussed

Ab initio predictions of the zero field splittings and the singlet–triplet transition strengths for the n → π* transition of selenoformaldehyde

1993 ◽  
Vol 71 (10) ◽  
pp. 1706-1712 ◽  
Author(s):  
D.C. Moule ◽  
L. Chantranupong ◽  
R.H. Judge ◽  
D.J. Clouthier
Keyword(s):  
Energy Levels ◽  
Random Phase ◽  
Open Shell ◽  
Oscillator Strengths ◽  
Basis Set ◽  
Zero Field ◽  
Zero Field Splitting ◽  
Hartree Fock ◽  
Lower Valence ◽  
Polarization Functions

The energy levels of the lower valence and Rydberg states of selenoformaldehyde, CH2Se, have been calculated by the SCF/CI method. Wavefunctions for the ROHF (restricted open shell Hartree–Fock) states were obtained with the Binnings–Curtis double-ζ basis set, augmented with Rydberg and polarization functions. Configuration interaction was applied to the parent configurations, PCMO (parent configuration molecular orbital). Oscillator strengths were evaluated for the allowed electric dipole transitions by the RPA (random phase approximation), and SOPPA (second-order polarization propagator approximation) methods. The spin-orbit contribution to the zero field splitting of the first triplet state, 3A2(n,π*) as well as the oscillator strengths to the three spin components were calculated by perturbation theory. These calculations predict that the Sx, Sy, and Sz components are shifted by −96.091,−96.707, and + 29.167 cm−1, respectively, from their unperturbed position. The oscillator strengths for the three components fx, fy, and fz of the 3A2(n,π*) ← 1A1(g.s.) transition were calculated to be 3.45 × 10−7, 1.15 × 10−7, and 173.0 × 10−7.

EPR Parameters and Local Atom-position Parameters for Co2+ Ions in CdS and CdSe Semiconductors

2004 ◽  
Vol 59 (11) ◽  
pp. 783-786 ◽  
Author(s):  
Wen-Chen Zheng ◽  
Xiao-Xuan Wu ◽  
Yang Mei ◽  
Jian Zi
Keyword(s):  
Coupling Parameter ◽  
Zero Field ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Cluster Approach ◽  
Zero Field Splitting ◽  
Trigonal Symmetry ◽  
Epr Parameters ◽  
Impurity Centers ◽  
Atom Position

The EPR parameters (zero-field splitting D and g factors gII, g⊥) of Co2+ ions in CdS and CdSe semiconductors are calculated from the high-order perturbation formulas based on the cluster approach for a 3d7 ion in trigonal symmetry. These formulas include the contribution to the EPR parameters from both the spin-orbit coupling parameter of the 3d7 ion and that of the ligand. From the calculations, the local atom-position parameters u (which are different from the corresponding values in the host crystals) for the Co2+ impurity centers in both semiconductors are estimated. The results are discussed

Single-Crystal Magnetic Properties of [Co(NH3)5(OH2)] [Cr(CN)6] Between 2 and 300 K

1992 ◽  
Vol 45 (11) ◽  
pp. 1899 ◽  
Author(s):  
PA Reynolds ◽  
CD Delfs ◽  
BN Figgis ◽  
B Moubaraki ◽  
KS Murray
Keyword(s):  
Ising Model ◽  
Field Model ◽  
Mean Field ◽  
Zero Field ◽  
Spin Orbit Coupling ◽  
Zero Field Splitting ◽  
Magnetic Exchange Interaction ◽  
Mean Field Model ◽  
Magnetic Exchange ◽  
The Mean

The magnetic susceptibilities along and perpendicular to the c axis (hexagonal setting) between 2.0 and 300 K at a magnetic field of 1.00 T, and the magnetizations at field strengths up to 5.00 T, are presented for single crystals of [Co(NH3)5(OH2)] [Cr(CN)6]. The results are interpreted in terms of zero-field splitting (2D) of the ground 4A2g term by spin-orbit coupling and of magnetic exchange interaction between the chromium atoms. The magnetic exchange is modelled as one of Ising or mean-field in type. The exchange is found to be quite small: J = -0.18(6) cm-1 if the Ising model is employed, and -0.03(1) cm-1 for the mean-field model. The model adopted for the exchange has a strong influence on the value of the parameter D obtained. When the Ising model is used D is deduced to be -0.28(9) cm-l; when the mean-field model is used D is -0.14(4) cm-l. The g-values deduced are in agreement with those from e.s.r. measurements at higher temperatures and do not depend on the exchange model. In any case, D is found to be sufficiently large that it must be considered in a polarized neutron diffraction experiment on the compound.

Zur paramagnetischen Elektronenresonanz metallorganischer Sandwich-Verbindungen, Teil I / The magnetic resonance properties of some sandwich compounds, part i

1972 ◽  
Vol 27 (7) ◽  
pp. 1082-1093
Author(s):  
R Krieger ◽  
J Voitländer
Keyword(s):  
Zero Field ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Zero Field Splitting ◽  
Field Splitting ◽  
Degenerate Ground State ◽  
Resonance Properties ◽  
Rhombic Distortion ◽  
Combined Action ◽  
Low Symmetry

AbstractThe zero-field splitting and g-values of manganocene and chromocene have been calculated. The wave functions were obtained by means of a self-consistent charge extended Huckel method. The calculated values g||=2.0034 and g⊥ = 2.0033 of manganocene agree fairly well with the experi­mental results obtained from ESR measurements. The very large computed zero-field splitting D= -0.24 cm-1 explains that there has been observed only one ESR transition though mangano­cene is in a spin-5/2 state. For chromocene no ESR transition has been found until now. We therefore studied the splitting of the orbitally degenerate ground state by the combined action of spin-orbit coupling and low-symmetry perturbation. The predicted splitting is strongly dependent on the magnitude of the rhombic distortion compared to the spin-orbit interaction. The g-values are highly anisotropic, with g|| =2.49 and g⊥ =1.97

Predicting phosphorescent lifetimes and zero-field splitting of organometallic complexes with time-dependent density functional theory including spin–orbit coupling

2014 ◽  
Vol 16 (28) ◽  
pp. 14523-14530 ◽  
Author(s):  
K. Mori ◽  
T. P. M. Goumans ◽  
E. van Lenthe ◽  
F. Wang
Keyword(s):  
Density Functional ◽  
Organometallic Complexes ◽  
Orbit Coupling ◽  
Zero Field ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Zero Field Splitting ◽  
Solvation Model ◽  
Functional Theory ◽  
Tddft Calculations

Experimental phosphorescent lifetimes for various organometallic complexes are well reproduced by spin–orbit coupling TDDFT calculations with a continuum solvation model.

scholarly journals Electronic fine structure calculation of [Gd(DOTA)(H2O)]– using LF-DFT: The zero field splitting

2012 ◽  
Vol 15 (2-3) ◽  
pp. 250-254 ◽  
Author(s):  
Florian Senn ◽  
Lothar Helm ◽  
Alain Borel ◽  
Claude A. Daul
Keyword(s):  
Fine Structure ◽  
Structure Calculation ◽  
Zero Field ◽  
Zero Field Splitting ◽  
Field Splitting

Theoretical study of spin–orbit coupling and zero-field splitting in the spin-forbidden two-state reaction between cobaltacyclopentadiene and isocyanate

2013 ◽  
Vol 59 (3) ◽  
pp. 286-296
Author(s):  
Lingling Lü ◽  
Xiaofang Wang ◽  
Yuancheng Zhu ◽  
Xinwen Liu ◽  
Kun Yuan ◽  
...  
Keyword(s):  
Theoretical Study ◽  
Orbit Coupling ◽  
Zero Field ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Zero Field Splitting ◽  
Field Splitting
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