Improved Pauli Hamiltonian for local-potential problems

1,315

992

We propose large-core correlation-consistent pseudopotential basis sets for the heavy p-block elements Ga-Kr and In-Xe. The basis sets are of cc-pVTZ and cc-pVQZ quality, and have been optimized for use with the large-core (valence-electrons only) Stuttgart-Dresden-Bonn relativistic pseudopotentials.Validation calculations on a variety of third-row and fourth-row diatomics suggest them to be comparable in quality to the all-electron cc-pVTZ and cc-pVQZ basis sets for lighter elements. Especially the SDB-cc-pVQZ basis set in conjunction with a core polarization potential (CPP) yields excellent agreement with experiment for compounds of the later heavy p-block elements.For accurate calculations on Ga (and, to a lesser extent, Ge) compounds, explicit treatment of 13 valence electrons appears to be desirable, while it seems inevitable for In compounds. For Ga and Ge, we propose correlation consistent basis sets extended for (3d) correlation. For accurate calculations on organometallic complexes of interest to homogenous catalysis, we recommend a combination of the standard cc-pVTZ basis set for first-and second-row elements, the presently derived SDB-cc-pVTZ basis set for heavier p-block elements, and for transition metals, the small-core [6s5p3d] Stuttgart-Dresden 1 basis set-RECP combination supplemented by (2f 1g) functions with exponents given in the Appendix to the present paper.

Section: Generation Of Basis Setsmentioning

confidence: 99%

Correlation consistent valence basis sets for use with the Stuttgart–Dresden–Bonn relativistic effective core potentials: The atoms Ga–Kr and In–Xe

Martin¹,

Sundermann²

2001

1,315

992

“…are the orbital-dependent mass-velocity plus Darwin potentials of Cowan-Griffin-Wood-Woring ͑related to but different from Pauli's mass-velocity and Darwin operators͒ 5,6 and the angular projectors made of spherical harmonics…”

Section: ͑3͒mentioning

confidence: 99%

“…Within the latter kind, the ab initio model potential method ͑AIMP͒ 3 resulted from the implementation of two ideas: 4 ͑i͒ the core model potentials are obtained directly from the frozen core orbitals, without resorting to parametrization procedures based on the valence orbitals, and ͑ii͒ the components of the core model potentials must mimic the operators that they substitute as much as possible, while reducing the computing time. Spin-free relativistic core AIMPs derived from atomic Cowan-Griffin calculations 5 and extended to include spin-orbit coupling effects according to Wood and Boring suggestions 6 constitute the so-called relativistic WB-AIMPs, 7 which are used with optimized valence basis sets. In addition to the nonrelativistic ones, the ingredients of the WB-AIMP method have been produced, successfully monitored, and used for the main-group elements and for the three series of transition metal elements.…”

Section: Introductionmentioning

confidence: 99%

The ab initio model potential method: Lanthanide and actinide elements

Seijo

Barandiarán

Harguindey

2001

106

In this paper we present relativistic core ab initio model potentials based on atomic Cowan-Griffin calculations, together with Wood-Boring spin-orbit operators and optimized Gaussian valence basis sets, for the lanthanide elements Ce to Lu and for the actinide elements Th to Lr. This completes the chemically relevant part of the Periodic Table. A ͓Kr,4d͔ core was chosen for Ce-Lu and a ͓Xe,4f ,5d͔ core was chosen for Th-Lr. Minimal (14s10p9d8 f )/͓2s1 p1d1 f ͔ and (14s10p11d9 f )/͓2s1 p1d1 f ͔ valence basis sets were, respectively, optimized for Ce-Lu and Th-Lr, and a ͓6s5 p5d4 f ͔ contraction is recommended for all these 28 elements in molecular calculations. The atomic and molecular results show the same good quality already observed for the main-group elements and the transition metal elements.

“…In consequence, a method is needed which reliably considers: ͑i͒ the scalar and spin-orbit coupling relativistic effects of uranium, ͑ii͒ a significant amount of electron correlation effects in a large number of states of the (UCl 6 ) 3Ϫ cluster, and ͑iii͒ the classical and quantum embedding effects brought about by the Cs 2 NaYCl 6 ionic host into the (UCl 6 ) 3Ϫ cluster. We have used the AIMP embedding method 21 for the third purpose, together with the Wood-Boring 22 -based effective core potential twocomponent relativistic Hamiltonian WB-AIMP 23 for the first one. The simultaneous treatment of electron correlation and spin-orbit coupling, which is very demanding here, has been handled by means of spin-orbit multireference configuration interaction calculations ͑MRCI͒ using the spin-free-stateshifted Hamiltonian, 24 which allows to transfer electron correlation effects from calculations with a spin-free Hamiltonian to calculations with a spin-orbit Hamiltonian.…”

Section: Details Of the Calculationsmentioning

confidence: 99%

Ab initio theoretical studies on U3+ and on the structure and spectroscopy of U3+ substitutional defects in Cs2NaYCl6, 5f 26d1 manifold

Seijo

Barandiarán

2003

In this paper we present the results of spin-orbit relativistic ab initio model potential embedded cluster calculations of the 5 f 2 6d 1 excited manifold of (UCl 6 ) 3Ϫ embedded in a reliable representation of the Cs 2 NaYCl 6 elpasolite host. They are aimed at interpreting the 5 f 3 →5 f 2 6d 1 absorption bands reported by Karbowiak et al. ͓J. Chem. Phys. 108, 10181 ͑1998͒.͔ An excellent agreement is found between the calculated energies of the absorption transitions from the ground state 5 f 3 1 ⌫ 8u ( 4 I 9/2 ) and the experimental data, which supports a detailed interpretation of the electronic nature of the absorption spectrum in the energy region 14 000-23 000 cm Ϫ1 . In particular, the three unidentified electronic origins that had been experimentally detected are now assigned, and the observed bands are interpreted as having multiple electronic origins. From the structural point of view, the excited states of the 5 f 2 6d 1 manifold are classified in two sets of main configuration 5 f 2 6d(t 2g ) 1 and 5 f 2 6d(e g ) 1 with bond distances R e ͓5 f 2 6d(t 2g ) 1 ͔ϽR e ͓5 f 3 ͔ ϽR e ͓5 f 2 6d(e g ) 1 ͔. The energies of the 5 f 2 6d 1 manifold of free U 3ϩ have also been calculated; experimental data on them are not available in the literature to the best of our knowledge. These results contribute to show that wave function based ab initio methods can provide useful structural and spectroscopic information, complementary to the experimental data, in studies on actinide ion impurities doping ionic hosts, where large manifolds of 5d nϪ1 6d 1 excited states are involved.