All-electron Gaussian basis sets of double zeta quality for the actinides

Abstract

For the actinides, two segmented all-electron basis sets of valence double zeta quality plus polarization functions (DZP) are developed. One of them must be used along with the non-relativistic Hamiltonian, whereas the other with the Douglas-Kroll-Hess (DKH) one. Adding diffuse functions of s, p, d, f, and g symmetries to the non-relativistic and relativistic sets, augmented basis sets are developed. These functions are essential to describe correctly electrons far away from the nuclei. For some compounds, geometric parameters, atomic charges and valence orbital populations of the actinides, and bond dissociation energies are calculated using the Becke 3-parameter (exchange) and the Lee, Yang, and Parr (correlation) functional in conjunction with the DZP-DKH basis set. For Am and No, the static electric mean dipole polarizabilities are also reported. Comparison with benchmark theoretical and experimental values found in the literature is carried out. It is verified that the performances of the relativistic compact size basis sets generated in this work are regular, efficient, and reliable. They will be extremely helpful in molecular property calculations that need explicitly to consider the core electrons.

Segmented Contracted Error-Consistent Basis Sets of Quadruple-ζ Valence Quality for One- and Two-Component Relativistic All-Electron Calculations

“…Relativistic ECPs allow for a cost-efficient and accurate description of most valence properties. , However, properties driven by the electron density in the core region such as nuclear magnetic resonance (NMR) shifts and coupling constants or core excitations in X-ray spectra are not easily accessible and are best treated within relativistic all-electron approaches based on the Dirac equation. − Dyall et al developed general contracted basis sets for the use in scalar-relativistic one-component (1c) and spin–orbit two-component or four-component (4c) calculations. − These are usually employed in an uncontracted fashion in one- and two-component treatments based on the block-diagonalization of the one-electron Dirac Hamiltonian. ANO basis sets optimized for scalar-relativistic treatments are also available. − The ANO-RCC bases were optimized with the second-order Douglas–Kroll–Hess (DKH2) Hamiltonian − and are thus commonly employed in their decontracted form in exact two-component (X2C) − studies. − Also, Peterson et al constructed DKH and X2C optimized correlation-consistent basis sets. − Segmented contracted relativistic all-electron basis sets were developed by the Jorge group − and the Sapporo group − for the DKH Hamiltonian. Furthermore, loosely contracted basis sets for scalar-relativistic treatments were presented by Pantazis and co-workers. − All of these approaches have their particular strengths, but still missing is a consistent series of quadruple-ζ bases for contemporary one- and two-component all-electron relativistic treatments that show similar errors all across the periodic table, yield an accurate description also for the innermost orbitals and properties relying on that, and can be efficiently evaluated in codes that are not explicitly optimized for generally contra...…”

Norm-Conserving Pseudopotentials and Basis Sets to Explore Actinide Chemistry in Complex Environments

“…Since their inclusion in the periodic table of elements by Seaborg, actinides have played a paramount role in science and human society. , Besides the applications in energy resources and industry, the potential usefulness of actinide-containing compounds has been extended to catalysis, − single molecular magnetism, − photoluminescence material, and superconductors. − Despite increasing attention on actinide chemistry, large-scale condensed-phase electronic structure simulations of actinide-containing systems are lacking due in a large part to challenges in the description of the huge number of electrons, especially the 5f-state electrons, as well as strong relativistic and electron correlation effects. The use of all-electron calculations with basis sets that consider relativistic effects will always be required to predict some actinide properties, for example, nuclear magnetic resonance. − However, the use of accurate pseudopotentials, that appropriately replace atomic core electrons and account for scalar relativistic effects, has been proven to be an effective treatment to model actinides with considerably reduced computational cost. − Computational modeling and simulations of actinide systems in the condensed phase are particularly challenging as pseudopotentials and companion basis sets have to be constructed to reduce the computational cost and achieve linear scaling for actinides in bulk solids, surfaces, and solutions with full explicit solvent boxes …”

An Examination of the Electron Densities in a Series of Tripodal Cobalt Complexes Bridged by Magnesium, Calcium, Strontium and Barium

“…The M06-2X functional performs reasonably well when benchmarked against both CCSD(T) and experimental results for structures, dissociation energies and vibrational frequencies of alkaline-earth compounds (11). The DZP-DKH (Douglas-Kroll-Hess) is a contracted Gaussian basis sets of double zeta valence qualities plus polarization functions, with the contraction coefficients optimized using the relativistic DKH Hamiltonian for elements from H to Kr (12) and from Cs to Rn (13). This theoretical level allows us to analyze and compare the complexes with the four alkaline-earth metals.…”