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Abstract: A Green's function formalism is used to calculate the energy of impurity modes associated with one and/or two magnetic impurities in the one-dimensional Heisenberg XXZ magnetic chain. The system can be tuned from the Heisenberg to the Ising model varying a parameter λ. A numerical study is performed showing two types of localized modes (s and p). The modes depend on λ and the degeneracy of the acoustic modes is broken. [Copyright &y& Elsevier]

Abstract: A Green''s function method is used to obtain the spectrum of excitations of two neighboring impurities in a semi-infinite ferromagnet. The equations of motion for Green''s functions are determined in the framework of the Heisenberg model. The energies of non-resonant localized modes are calculated as a function of the interaction parameters for the exchange coupling between impurity–spin pairs, host–spin pairs, and impurity–host neighbors, as well as the effective field parameter at the impurity sites. With two impurities the system is less symmetric and has more localized modes when compared with a single impurity case. [Copyright &y& Elsevier]

Abstract: A Green''s function method is used to obtain the spectrum of spin excitations associated with a linear array of magnetic impurities implanted in a ferromagnetic thin film. The equations of motion for the Green''s functions of the anisotropic film are written in the framework of the Ising model in a transverse field. The frequencies of localized modes are calculated as a function of the interaction parameters for the exchange coupling between impurity-spin pairs, host-spin pairs, and impurity-host neighbors, as well as the effective field parameter at the impurity sites. [Copyright &y& Elsevier]

Abstract: A Green''s function formalism is used to calculate the spectrum of excitations of two neighboring impurities implanted in a semi-infinite ferromagnetic. The equations of motion for the Green''s functions are determined in the framework of the Ising model in a transverse field and results are given for the effect of the exchange coupling, position and orientation of the impurities on the spectra of localized spin wave modes. [Copyright &y& Elsevier]

Abstract: A Green''s function formalism is used to calculate the spectrum of localized modes of an impurity layer implanted within a ferromagnetic thin film. The equations of motion for the Green''s functions are determined in the framework of the Ising model in a transverse field. We show that depending on the thickness, exchange and effective field parameters, there is a “crossover” effect between the surface modes and impurity localized modes. For thicker films the results show that the degeneracy of the surface modes can be lifted by the presence of an impurity layer. [Copyright &y& Elsevier]

Flavonoids are secondary metabolites of plants which perform various functions. One subclass of flavonoid is auronol that can present immunostimulating activity. In this work Fourier-Transform Infrared with Attenuated Total Reflectance (FTIR-ATR) and Fourier-Transform Raman (FT-Raman) spectra of an auronol, derriobtusone A (C 18 H 12 O 4 ), were obtained at room temperature. Theoretical calculations using Density Functional Theory (DFT) were performed in order to assign the normal modes and to interpret the spectra of the derriobtusone A molecule. The FTIR-ATR and FT-Raman spectra of the crystal, were recorded at room temperature in the regions 600 cm −1 to 4000 cm −1 and 40 cm −1 to 4000 cm −1 , respectively. The normal modes of vibrations were obtained using Density Functional Theory with B3LYP functional and 6-31G+ (d,p) basis set. The calculated frequencies are in good agreement with those obtained experimentally. Detailed assignments of the normal modes present in both the Fourier-Transform infrared and the Fourier-Transform Raman spectra of the crystal are given. [ABSTRACT FROM AUTHOR]