Calibration of S119n isomer shift using<i>ab initio</i>wave function methods

Kurian, Reshmi; Filatov, Michael

doi:10.1063/1.3094259

Cited by 19 publications

(23 citation statements)

References 72 publications

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“…This linear relationship has also been observed in the complete active space self-consistent field (CASSCF) calculations on a small test set 67. For an alternative, non-empirical computation of the isomer shift, which employs derivatives of the electronic energy with respect to the size of the non-point-like nucleus and which is more laborious, see Refs 18,51,68,69. The slope α and intercept C are typically obtained with the least-squares method using a parametrization set of experimental isomer shifts and theoretically-computed densities ρ (0).…”

Section: Isomer Shiftmentioning

confidence: 56%

Prediction of ⁵⁷Fe Mössbauer Parameters by Density Functional Theory: A Benchmark Study

Bochevarov

Friesner

Lippard

2010

J. Chem. Theory Comput.

130

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We report the performance of eight density functionals (B3LYP, BPW91, OLYP, O3LYP, M06, M06-2X, PBE, and SVWN5) in two Gaussian basis sets (Wachters and Partridge-1 on iron atoms; cc-pVDZ on the rest of atoms) for the prediction of the isomer shift (IS) and the quadrupole splitting (QS) parameters of Mössbauer spectroscopy. Two sources of geometry (density functional theory-optimized and X-ray) are used. Our data set consists of 31 iron-containing compounds (35 signals), the Mössbauer spectra of which were determined at liquid helium temperature and where the X-ray geometries are known. Our results indicate that the larger and uncontracted Partridge-1 basis set produces slightly more accurate linear correlations of electronic density used for the prediction of IS and noticeably more accurate results for the QS parameter. We confirm and discuss the earlier observation of Noodleman and co-workers that different oxidation states of iron produce different IS calibration lines. The B3LYP and O3LYP functionals have the lowest errors for either IS or QS. BPW91, OLYP, PBE, and M06 have a mixed success whereas SVWN5 and M06-2X demonstrate the worst performance. Finally, our calibrations and conclusions regarding the best functional to compute the Mössbauer characteristics are applied to candidate structures for the peroxo and Q intermediates of the enzyme methane monooxygenase hydroxylase (MMOH), and compared to experimental data in the literature.

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Section: Isomer Shiftmentioning

confidence: 56%

Prediction of ⁵⁷Fe Mössbauer Parameters by Density Functional Theory: A Benchmark Study

Bochevarov

Friesner

Lippard

2010

J. Chem. Theory Comput.

130

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“…1,2,8,9 The electron density in the vicinity of the nucleus for which the isotope shift was calculated for was obtained from the solution to the Dirac equation for a single electron in the Coulomb potential of a point-charge nucleus and was then expressed in terms of the nonrelativistic electron density at the position of the nucleus. [16][17][18] Recently, an alternative technique to obtain contact densities within isomer-shift calculations was proposed, [20][21][22] where the contact-density is treated as an energy derivative with respect to the nuclear radius. 8 Then, more elaborate fully relativistic approaches based on the Dirac-Coulomb Hamiltonian in combination with a finite nuclear charge distribution model to obtain contact densities were developed.…”

Section: Introductionmentioning

confidence: 99%

Basis set representation of the electron density at an atomic nucleus

Mastalerz

Widmark

Roos

et al. 2010

The Journal of Chemical Physics

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In this paper a detailed investigation of the basis set convergence for the calculation of relativistic electron densities at the position of finite-sized atomic nuclei is presented. The development of Gauss-type basis sets for such electron densities is reported and the effect of different contraction schemes is studied. Results are then presented for picture-change corrected calculations based on the Douglas-Kroll-Hess Hamiltonian. Moreover, the role of electron correlation, the effect of the numerical integration accuracy in density functional calculations, and the convergence with respect to the order of the Douglas-Kroll-Hess Hamiltonian and the picture-change-transformed property operator are studied.

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“…By employing an extendednucleus model, one may also go beyond the contact density approximation and explicitly calculate the change in nucleus-electron interaction corresponding to the nuclear transition measured in Mössbauer spectroscopy. This approach has been pursued by Filatov and co-workers [19][20][21][22][23] who introduce a difference in radius between the ground-and excited state nucleus as a finite perturbation that can be used to numerically differentiate the electronic energy. An added advantage is that such a finite difference scheme also works for methods for which it is difficult to obtain the relaxed density directly.…”

Section: Introductionmentioning

confidence: 99%

Mössbauer spectroscopy for heavy elements: a relativistic benchmark study of mercury

Knecht

Fux

Meer³

et al. 2011

Theor Chem Acc

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The electrostatic contribution to the Mössbauer isomer shift of mercury for the series HgF n (n = 1, 2, 4) with respect to the neutral atom has been investigated in the framework of four-and two-component relativistic theory. Replacing the integration of the electron density over the nuclear volume by the contact density (that is, the electron density at the nucleus) leads to a 10% overestimation of the isomer shift. The systematic nature of this error suggests that it can be incorporated into a correction factor, thus justifying the use of the contact density for the calculation of the Mössbauer isomer shift. The performance of a large selection of density functionals for the calculation of contact densities has been assessed by comparing with finite-field four-component relativistic coupled-cluster with single and double and perturbative triple excitations [CCSD(T)] calculations. For the absolute contact density of the mercury atom, the Density Functional Theory (DFT) calculations are in error by about 0.5%, a result that must be judged against the observation that the change in contact density along the series HgF n (n = 1, 2, 4), relevant for the isomer shift, is on the order of 50 ppm with respect to absolute densities. Contrary to previous studies of the 57 Fe isomer shift (F Neese, Inorg Chim Acta 332:181, 2002), for mercury, DFT is not able to reproduce the trends in the isomer shift provided by reference data, in our case CCSD(T) calculations, notably the non-monotonous decrease in the contact density along the series HgF n (n = 1, 2, 4). Projection analysis shows the expected reduction of the 6s 1/2 population at the mercury center with an increasing number of ligands, but also brings into light an opposing effect, namely the increasing polarization of the 6s 1/2 orbital due to increasing effective charge of the mercury atom, which explains the nonmonotonous behavior of the contact density along the series. The same analysis shows increasing covalent contributions to bonding along the series with the effective charge of the mercury atom reaching a maximum of around ?2 for HgF 4 at the DFT level, far from the formal charge ?4 suggested by the oxidation state of this recently observed species. Whereas the geometries for the linear HgF 2 and square-planar HgF 4 molecules were taken from previous computational studies, we optimized the equilibrium distance of HgF at the four-component Fock-space CCSD/aug-cc-pVQZ level, giving spectroscopic constants r e = 2.007 Å and x e = 513.5 cm -1 .Dedicated to Professor Pekka Pyykkö on the occasion of his 70th birthday and published as part of the Pyykkö Festschrift Issue.Electronic supplementary material The online version of this article

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Calibration of S119n isomer shift usingab initiowave function methods

Cited by 19 publications

References 72 publications

Prediction of ⁵⁷Fe Mössbauer Parameters by Density Functional Theory: A Benchmark Study

Prediction of ⁵⁷Fe Mössbauer Parameters by Density Functional Theory: A Benchmark Study

Basis set representation of the electron density at an atomic nucleus

Mössbauer spectroscopy for heavy elements: a relativistic benchmark study of mercury

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Calibration of S119n isomer shift usingab initiowave function methods

Cited by 19 publications

References 72 publications

Prediction of 57Fe Mössbauer Parameters by Density Functional Theory: A Benchmark Study

Prediction of 57Fe Mössbauer Parameters by Density Functional Theory: A Benchmark Study

Basis set representation of the electron density at an atomic nucleus

Mössbauer spectroscopy for heavy elements: a relativistic benchmark study of mercury

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Product

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Prediction of ⁵⁷Fe Mössbauer Parameters by Density Functional Theory: A Benchmark Study

Prediction of ⁵⁷Fe Mössbauer Parameters by Density Functional Theory: A Benchmark Study