arXiv subjects
Publications and source records attributed to Alfred Xaver Trautwein.
Density functional methods have been applied to calculate the quadrupole splitting of a series of iron(II) spin crossover complexes. Experimental and calculated values are in reasonable agreement. In one case spin-orbit coupling is necessary to explain the very small quadrupole splitting value of 0.77 mm/s at 293 K for a high-spin isomer.
Nuclear inelastic scattering of synchrotron radiation has been used now since 10 years as a tool for vibrational spectroscopy. This method has turned out especially useful in case of large molecules that contain a Mössbauer active metal center. Recent applications to iron-sulfur proteins, to iron(II) spin crossover complexes and to tin-DNA complexes are discussed. Special emphasis is given to the combination of nuclear inelastic scattering and density functional calculations.
Nuclear inelastic scattering (NIS) of synchrotron radiation has been used to investigate the dynamics of tin ions chelated by DNA. Theoretical NIS spectra have been simulated with the help of density functional theory (DFT) calculations using 12 models for different binding sites of the tin ion in (CH3)Sn(DNAPhosphate)2. The simulated spectra are compared with the measured spectrum of the tin-DNA complex.
Nuclear inelastic scattering in conjunction with density functional theory (DFT) calculations has been applied for the identification of vibrational modes of the high-spin ferric and the high-spin ferrous iron-sulfur center of a rubredoxin-type protein from the thermophylic bacterium Pyrococcus abysii.
Density functional theory (DFT) provides a theoretical framework for efficient and fairly accurate calculations of the electronic structure of molecules and crystals. The main features of density functional theory are described and DFT methods are compared with wavefunction-based methods like the Hartree-Fock approach. Some recent applications of DFT to spin crossover complexes are reviewed, e.g., the calculation of Mössbauer parameters, of vibrational modes and of differences of entropy, vibrational energy, and total electronic energy between high-spin and low-spin isomers.
Density functional theory (DFT) calculations have been performed for the high-spin (HS) and low-spin (LS) isomers of a series of iron(II) spin crossover complexes with nitrogen ligands. The calculated charge densities have been analyzed in the framework of the quantum theory of atoms in molecules (QTAIM). For a number of iron(II) complexes with substituted tris(pyrazolyl) ligands the energy difference between HS and LS isomers, the spin state splitting, has been decomposed into atomic contributions in order to rationalize changes of the spin state splitting due to substituent effects.
Nuclear resonant forward scattering (NFS) and nuclear inelastic scattering (NIS) of synchrotron radiation are fairly recent spectroscopic methods for the investigation of complexes containing Mössbauer-active transition metal ions. NFS, which can be regarded as Mössbauer spectroscopy in the time domain, overcomes some limitations of conventional Mössbauer spectroscopy as has been demonstrated especially for bioinorganic compounds. NIS extends the energy range of conventional Mössbauer spectroscopy to the range of molecular vibrations. Since NIS is sensitive only to the mean-square displacement of Mössbauer nuclei it can be used as site-selective vibrational spectroscopy. It complements usefully comparable techniques such as IR or Raman spectroscopy. Examples are given for applications to spin crossover complexes, nitroprusside compounds, heme model complexes and myoglobin.