Theoretical investigations of the local distortion and electron paramagnetic resonance parameter for CdCl2：V^2＋ and CsMgX3：V^2＋（X=Cl,Br） systems

This paper systematically investigates the local distortion and electron paramagnetic resonance (EPR) parameter for CdCl 2 :V 2+ and CsMgX 3 :V 2+ (X=Cl, Br) systems on the basis of the complete energy matrix, in which not only the contributions due to the spin–orbit coupling of the central ions but also that of the ligands are considered. To describe the difference of overlapping between d-orbits and p orbit, two spin–orbit coupling coefficients are introduced. By simulating the crystal field parameter and EPR parameter, the local distortion parameters are studied and the relationships between the EPR parameter and the spin–orbit coupling coefficients as well as divergent parameter are discussed. These results show that the local structures exhibit compression distortion for CdCl 2 :V 2+ and elongation distortions for CsMgX 3 :V 2+ (X=Cl, Br), respectively. It notes that the empirical formula R ≈ R H + (r i-r h )/2 is not suitable for CdCl 2 :V 2+ and CsMgX 3 :V 2+ (X=Cl, Br) systems. The contributions of ligand to spin–orbit coupling interaction cannot be neglected for strong covalent systems, especially for V 2+ doped in CsMgBr 3 :V 2+ .

Theoretical investigations of the local distortion and electron paramagnetic resonance parameter for CdCl2:V2+ and CsMgX3:V2+ (X=Cl, Br) systems

This paper systematically investigates the localdistortion and electron paramagnetic resonance (EPR) parameter forCdCl₂:V²⁼ and CsMg$X₃:V²⁼ ($X$=Cl, Br)systems on the basis of the complete energy matrix, in which notonly the contributions due to the spin--orbit coupling of thecentral ions but also that of the ligands are considered. Todescribe the difference of overlapping between d-orbits and porbit, two spin--orbit coupling coefficients are introduced. Bysimulating the crystal field parameter and EPR parameter, the localdistortion parameters are studied and therelationships between the EPR parameter and the spin--orbit couplingcoefficients as well as divergent parameter are discussed. Theseresults show that the local structures exhibit compressiondistortion for CdCl₂:V²⁼ and elongation distortions for CsMg$X₃:V$^{2 +}$ ($X$=Cl, Br), respectively. It notes that the empirical formula$R approx R_{rm H} + (r_{rm i} - r_{rm h} ) / 2$ is not suitablefor CdCl₂:V²⁼ and CsMg$X₃:V²⁼ ($X$=Cl, Br)systems. The contributions of ligand to spin--orbit couplinginteraction cannot be neglected for strong covalent systems,especially for V²⁼ doped in CsMgBr$₃:V²⁼.