ChemInform Abstract: Relativistic Pseudopotentials: Their Development and Scope of Applications

Theoretical Chemistry, University of Cologne, Greinstrasse 4, 50939 Cologne, Germany.
Chemical Reviews (Impact Factor: 46.57). 09/2011; 112(1):403-80. DOI: 10.1021/cr2001383
Source: PubMed


The most important aspects of the theoretical background of effective core potentials (ECP), which include the pseudopotential (PP) and the model potential (MP) approach, are described. The commonly used ECP method does not only have the advantage to reduce the computational effort compared to an all-electron (AE) calculation by limiting the number of electrons treated explicitly but also allows an implicit incorporation of the most important relativistic effects. The bond contractions and expansions may occur parallel to orbital contractions and expansions but cannot necessarily be explained to be caused by them. The MP approach for atoms represents an important link between the full AE calculation and the PP calculations. Semiempirical PPs and corresponding CPPs were generated by Igel et al. for most of the main group elements by fitting the spectra of the one-valence electron ions for PP and CPP.

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    • "and a k lj are parameters adjusted by a least-squares fit to the valence spectrum of an atom obtained from all-electron multi-configuration Dirac–Fock–Breit calculations, including quantum electrodynamic effects if required [51], and often a simple Gaussian expansion is chosen with n k lj = 0. In this way relativistic ECPs for the superheavy elements from Rg to element 120 have been adjusted [67] [68] leading to results in a good agreement with more accurate four-component calculations [99]. "
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    • "Ideally all-electron calculations should be performed to obtain accurate results, but with large computational cost in order to resolve the sharp gradient of core orbitals and the oscillation of valance orbitals in the neighborhood of nuclei. A more practical way striking the balance between accuracy and efficiency is to employ effective core potentials [44], in which the core electrons are frozen and the valance-only problem is solved. The pseudopotential technique is one branch of effective core potential approaches. "
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