Browsing by Author "Frauenheim, Thomas"

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Automatized Parameterization of the Density-functional Tight-binding Method. II. Two-center Integrals
(2016-01-01)
Witek, Henryk A.
;
Chou, Chien-Pin
;
Mazur, Grzegorz
;
Nishimura, Yoshifumi
;
Irle, Stephan
We present an efficient numerical integration scheme (TWOCENT) to be used in the context of automatized parameterization of the density-functional tight-binding (DFTB) method. The accuracy of the integration process is assessed and its range of applicability is discussed. The functionality of the developed code is tested by reproducing the electronic portion of the existing mio parameter sets and by reproducing a series of reference DFT band structures of elemental solids.
Automatized Parameterization of the Density-functional Tight-binding Method. II. Two-center Integrals
(2016-01)
Witek, Henryk A.
;
Chou, Chien-Pin
;
Mazur, Grzegorz
;
Nishimura, Yoshifumi
;
Irle, Stephan
We present an efficient numerical integration scheme (TWOCENT) to be used in the context of automatized parameterization of the density-functional tight-binding (DFTB) method. The accuracy of the integration process is assessed and its range of applicability is discussed. The functionality of the developed code is tested by reproducing the electronic portion of the existing mio parameter sets and by reproducing a series of reference DFT band structures of elemental solids.
Relativistic parametrization of the self-consistent-charge density-functional tight-binding method. 1. Atomic wave functions and energies
(2007-07-05)
Witek, Henryk A.
;
Koehler, Christof
;
Frauenheim, Thomas
;
Morokuma, Keiji
;
Elstner, Marcus
A detailed treatment of a confined relativistic atom, needed as an initial step for the parametrization of the self-consistent-charge density-functional tight-binding method, is presented and discussed. The required one-component quantities, i.e., orbital energies, orbital wave functions, and Hubbard parameters, are obtained by weighted averaging of the corresponding numbers determined for the atomic spinors. The wave function and density confinement is achieved by introducing the Woods-Saxon potential in the atomic four-component Dirac-Kohn-Sham problem. The effect of the additional confining potential on energy eigenvalues and the shape of atomic wave functions and densities is discussed and numerical examples are presented for the valence spinors of carbon, germanium, and lead.