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The Accuracy of the Pseudopotential Approximation within Density‐Functional Theory
Author(s) -
Porezag D.,
Pederson M.R.,
Liu A.Y.
Publication year - 2000
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/(sici)1521-3951(200001)217:1<219::aid-pssb219>3.0.co;2-v
Subject(s) - pseudopotential , density functional theory , ab initio , linearization , ab initio quantum chemistry methods , spin (aerodynamics) , core (optical fiber) , range (aeronautics) , physics , atomic physics , nonlinear system , chemistry , quantum mechanics , molecule , materials science , thermodynamics , optics , composite material
We have investigated the accuracy of pseudopotential (PSP) density‐functional calculations with respect to the corresponding all‐electron (AE) results for a variety of atoms and small molecules. It is found that most of the deviations between ab‐initio PSP and AE calculations are due to the linearization of the exchange‐correlation functional within the PSP approach. This problem can be eliminated by applying nonlinear core corrections (NLCC). We find that a correct description of spin‐polarized states requires the NLCC, even for first‐row atoms. This is essential for simulations of magnetic systems and reaction processes which involve radicals. The NLCC is also essential for a realistic description of elements with more long‐range core states such as alkali atoms. A further improvement of pseudopotential accuracy may be achieved by explicitly including semi‐core states in the calculation.