Dresden 2009 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 21: Methods: Electronic structure theory I

O 21.2: Vortrag

Dienstag, 24. März 2009, 10:45–11:00, SCH A316

Scalar relativistic schemes for all-electron DFT with atom-centered basis functions — Paula Havu, •Volker Blum, and Matthias Scheffler — Fritz-Haber-Institut der Max-Planck-Gesellschaft, D-14195 Berlin, Germany

Numeric atom-centered orbitals are an efficient, accurate basis choice for all-electron electronic structure theory [1]. For seamless efficiency and accuracy, a one-component (two with spin) Schrödinger-like equation is computationally most convenient, but for most elements (Z30), relativistic effects arising near the nucleus cannot be ignored. Dirac’s equation can simply be rewritten in a “scalar-relativistic” (one-component) form, but with a separate Hamiltonian for each eigenstate. For some paradigm test systems [e.g., the Au dimer; CO adsorption on Pt(111)], we here benchmark the accuracy of a hierarchy of scalar-relativistic schemes that circumvent the state dependence: (i) the unsatisfactory “zero-order regular approximation” (ZORA), which simply neglects the state dependence; (ii) a restriction of ZORA to only the atomic center of each basis function (“atomic ZORA”) and (iii) a perturbative rescaling of all ZORA eigenvalues (“scaled ZORA” [2]), which both recover geometries and binding energies within a few 10 meV of benchmark full-potential linearized augmented plane wave [FP-(L)APW] calculations; and (iv) a separate, exact treatment of all non-overlapping core states, which then necessitates only small further (scaled) ZORA-like approximations to the extended semicore and valence states. [1] V. Blum et al., Comp. Phys. Comm., accepted (2008). [2] E. van Lenthe et al., J. Chem. Phys. 101, 9783 (1994).