Performance of nonrelativistic and quasi-relativistic hybrid DFT for the prediction of electric and magnetic hyperfine parameters in 57Fe mössbauer spectra
57Fe electric and magnetic hyperfine parameters were calculated for a series of 10 iron model complexes, covering a wide range of oxidation and spin states. Employing the B3LYP hybrid method, results from nonrelativistic density functional theory (DFT) and quasi-relativistic DFT within the zero-orde...
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2005
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paper:paper_00201669_v44_n7_p2245_Sinnecker2023-06-08T14:40:33Z Performance of nonrelativistic and quasi-relativistic hybrid DFT for the prediction of electric and magnetic hyperfine parameters in 57Fe mössbauer spectra Slep, Leonardo Daniel ferric ion iron 57 iron complex acceleration anisotropy article calculation correlation analysis density density functional theory electric field electric potential electron spin resonance hybrid hypothesis isomer magnetism measurement Mossbauer spectroscopy oxidation parameter prediction technique zero order regular approximation 57Fe electric and magnetic hyperfine parameters were calculated for a series of 10 iron model complexes, covering a wide range of oxidation and spin states. Employing the B3LYP hybrid method, results from nonrelativistic density functional theory (DFT) and quasi-relativistic DFT within the zero-order regular approximation (ZORA) were compared. Electron densities at the iron nuclei were calculated and correlated with experimental isomer shifts. It was shown that the fit parameters do not depend on a specific training set of iron complexes and are, therefore, more universal than might be expected. The nonrelativistic and quasi-relativistic electron densities gave fit parameters of similar quality; the ZORA densities are only shifted by a factor of 1.32, upward in the direction of the four-component Dirac-Fock value. From a correlation of calculated electric field gradients and experimental quadrupole splittings, the value of the 57Fe nuclear quadrupole moment was redetermined to a value of 0.16 barn, in good agreement with other studies. The ZORA approach gave no additional improvement of the calculated quadrupole splittings in comparison to the nonrelativistic approach. The comparison of the calculated and measured 57Fe isotropic hyperfine coupling constants (hfcc's) revealed that both the ZORA approach and the inclusion of spin-orbit contributions lead to better agreement between theory and experiment in comparison to the nonrelativistic results. For all iron complexes with small spin-orbit contributions (high-spin ferric and ferryl systems), a distinct underestimation of the isotropic hfcc's was found. Scaling factors of 1.81 (nonrelativistic DFT) and 1.69 (ZORA) are suggested. The calculated 57Fe isotropic hfcc's of the remaining model systems (low-spin ferric and high-spin ferrous systems) contain 10-50% second-order contributions and were found to be in reasonable agreement with the experimental results. This is assumed to be the consequence of error cancellation because g-tensor calculations for these systems are of poor quality with the existing DFT approaches. Excellent agreement between theory and experiment was found for the 57Fe anisotropic hfcc's. Finally, all of the obtained fit parameters were used for an application study of the [Fe(H2O)6] 3+ ion. The calculated spectroscopic data are in good agreement with the Mössbauer and electron paramagnetic resonance results discussed in detail in a forthcoming paper. © 2005 American Chemical Society. Fil:Slep, L.D. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. 2005 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00201669_v44_n7_p2245_Sinnecker http://hdl.handle.net/20.500.12110/paper_00201669_v44_n7_p2245_Sinnecker |
| institution |
Universidad de Buenos Aires |
| institution_str |
I-28 |
| repository_str |
R-134 |
| collection |
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
| topic |
ferric ion iron 57 iron complex acceleration anisotropy article calculation correlation analysis density density functional theory electric field electric potential electron spin resonance hybrid hypothesis isomer magnetism measurement Mossbauer spectroscopy oxidation parameter prediction technique zero order regular approximation |
| spellingShingle |
ferric ion iron 57 iron complex acceleration anisotropy article calculation correlation analysis density density functional theory electric field electric potential electron spin resonance hybrid hypothesis isomer magnetism measurement Mossbauer spectroscopy oxidation parameter prediction technique zero order regular approximation Slep, Leonardo Daniel Performance of nonrelativistic and quasi-relativistic hybrid DFT for the prediction of electric and magnetic hyperfine parameters in 57Fe mössbauer spectra |
| topic_facet |
ferric ion iron 57 iron complex acceleration anisotropy article calculation correlation analysis density density functional theory electric field electric potential electron spin resonance hybrid hypothesis isomer magnetism measurement Mossbauer spectroscopy oxidation parameter prediction technique zero order regular approximation |
| description |
57Fe electric and magnetic hyperfine parameters were calculated for a series of 10 iron model complexes, covering a wide range of oxidation and spin states. Employing the B3LYP hybrid method, results from nonrelativistic density functional theory (DFT) and quasi-relativistic DFT within the zero-order regular approximation (ZORA) were compared. Electron densities at the iron nuclei were calculated and correlated with experimental isomer shifts. It was shown that the fit parameters do not depend on a specific training set of iron complexes and are, therefore, more universal than might be expected. The nonrelativistic and quasi-relativistic electron densities gave fit parameters of similar quality; the ZORA densities are only shifted by a factor of 1.32, upward in the direction of the four-component Dirac-Fock value. From a correlation of calculated electric field gradients and experimental quadrupole splittings, the value of the 57Fe nuclear quadrupole moment was redetermined to a value of 0.16 barn, in good agreement with other studies. The ZORA approach gave no additional improvement of the calculated quadrupole splittings in comparison to the nonrelativistic approach. The comparison of the calculated and measured 57Fe isotropic hyperfine coupling constants (hfcc's) revealed that both the ZORA approach and the inclusion of spin-orbit contributions lead to better agreement between theory and experiment in comparison to the nonrelativistic results. For all iron complexes with small spin-orbit contributions (high-spin ferric and ferryl systems), a distinct underestimation of the isotropic hfcc's was found. Scaling factors of 1.81 (nonrelativistic DFT) and 1.69 (ZORA) are suggested. The calculated 57Fe isotropic hfcc's of the remaining model systems (low-spin ferric and high-spin ferrous systems) contain 10-50% second-order contributions and were found to be in reasonable agreement with the experimental results. This is assumed to be the consequence of error cancellation because g-tensor calculations for these systems are of poor quality with the existing DFT approaches. Excellent agreement between theory and experiment was found for the 57Fe anisotropic hfcc's. Finally, all of the obtained fit parameters were used for an application study of the [Fe(H2O)6] 3+ ion. The calculated spectroscopic data are in good agreement with the Mössbauer and electron paramagnetic resonance results discussed in detail in a forthcoming paper. © 2005 American Chemical Society. |
| author |
Slep, Leonardo Daniel |
| author_facet |
Slep, Leonardo Daniel |
| author_sort |
Slep, Leonardo Daniel |
| title |
Performance of nonrelativistic and quasi-relativistic hybrid DFT for the prediction of electric and magnetic hyperfine parameters in 57Fe mössbauer spectra |
| title_short |
Performance of nonrelativistic and quasi-relativistic hybrid DFT for the prediction of electric and magnetic hyperfine parameters in 57Fe mössbauer spectra |
| title_full |
Performance of nonrelativistic and quasi-relativistic hybrid DFT for the prediction of electric and magnetic hyperfine parameters in 57Fe mössbauer spectra |
| title_fullStr |
Performance of nonrelativistic and quasi-relativistic hybrid DFT for the prediction of electric and magnetic hyperfine parameters in 57Fe mössbauer spectra |
| title_full_unstemmed |
Performance of nonrelativistic and quasi-relativistic hybrid DFT for the prediction of electric and magnetic hyperfine parameters in 57Fe mössbauer spectra |
| title_sort |
performance of nonrelativistic and quasi-relativistic hybrid dft for the prediction of electric and magnetic hyperfine parameters in 57fe mössbauer spectra |
| publishDate |
2005 |
| url |
https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00201669_v44_n7_p2245_Sinnecker http://hdl.handle.net/20.500.12110/paper_00201669_v44_n7_p2245_Sinnecker |
| work_keys_str_mv |
AT slepleonardodaniel performanceofnonrelativisticandquasirelativistichybriddftforthepredictionofelectricandmagnetichyperfineparametersin57femossbauerspectra |
| _version_ |
1768542018357690368 |