The nuclear electric quadrupole moment of antimony from the molecular method

Abstract

Relativistic Dirac-Coulomb ͑DC͒ Hartree-Fock calculations are employed to obtain the analytic electric field gradient ͑EFG͒ on the antimony nucleus in the SbN, SbP, SbF, and SbCl molecules. The electronic correlation contribution to the EFGs is included with the DC-CCSD͑T͒ and DC-CCSD-T approaches, also in the four-component framework, using a finite-difference method. The total EFG results, along with the experimental nuclear quadrupole coupling constants from microwave spectroscopy, allow to derive the nuclear quadrupole moments of 121 Sb and 123 Sb, respectively, as −543͑11͒ and −692͑14͒ mb.

Nuclear electric quadrupole moment of gold

“…A particular problem lies in the fact that high basis function exponents create large perturbations even with rather small field strengths. 10 We found EFG instabilities also in our series of molecules but, based on a series of tests, we have been able to reach stable EFG results using an absolute field strength of 1 ϫ 10 −8 a.u. and deleting the first and the first two tight p functions of the gold basis sets VTZ and VQZ, respectively.…”

“…The finite-difference method has a major limitation in the finite-field strength that can be used. 10,17 This strength should be small enough to remain in the linear regime, while at the same time it should be large enough to prevent numerical inaccuracies due incomplete convergence of the iterative procedures and other sources of numerical noise. A particular problem lies in the fact that high basis function exponents create large perturbations even with rather small field strengths.…”

First principles calculation of Mössbauer isomer shift

“…In this respect, development of the first principles approaches, which go beyond the traditional perturbational treatment of isomer shift and incorporate inherently the aforementioned effects of relativity and electron correlation, should lead to a substantial progress towards a more accurate theoretical interpretation of Mössbauer spectra. In combination with the high-level computational approaches to the calculation of other nuclear parameters, such as quadrupole splitting [140][141][142][143][144][145][146][147][148][149] and hyperfine splitting constants [150][151][152], these developments will ultimately lead to a full theoretical characterization of Mössbauer spectra and to deeper understanding of their relationship with the electronic structure of materials.…”

New density functional parameterizations to accurate calculations of electric field gradient variations among compounds

“…Hence, when available, the reference data of EFGs for comparison are those from DC-CCSD-T results. [10,12,13] Otherwise, DC-CCSD(T) values are selected. [9,11] Although the DC-CCSD-T or DC-CCSD(T) EFGs can still suffer from errors associated with an incomplete treatment of electron correlation, the general experience acquired along the years shows that these levels are commonly quite accurate.…”