Spin density functional methods

Energy production maximum of magnets LSDF Local spin-density functional (method)... 

V. G. Malkin, M. Kaupp. Calculation of zero-field splitting parameters Comparison of a two-component noncolinear spin-density-functional method and a one-component perturbational approach. 

This introduction closes with a brief presentation of the Kohn-Sham [6] spin-density functional method, the most widely-used method of electronic-structure calculation in condensed-matter physics and one of the most widely-used methods in quantum chemistry. We seek the groimd-state total energy E and spin densities n (r), n (r) for a collection of N electrons interacting with one another and with an external potential w(r) (due to the nuclei in most practical cases). These are foimd by the selfconsistent solution of an auxiliary (fictitious) one-electron Schrodinger equation ... 

For H at T in Si, Katayama-Yoshida and Shindo (1983, 1985) used a Green s function method to carry out spin-density-functional calculations. They found a reduction of the spin density by a factor 0.41. However, their results are subject to some uncertainty because they obtained an erroneous result for the position of the defect state in the band gap, probably due to an insufficiently converged LCAO basis set. 

Also pure density-functional methods combined with plane-wave basis sets and ultrasoft pseudopotentials [58] were used in our studies of extended systems [59]. The computational efficiency of these methods enables larger systems and to some extent dynamical processes to be studied. Generalized-gradient approximation (GGA) or spin-polarized GGA DFT functionals [60, 61] were employed in the electronic structure calculations. 

Naumov S, Beckert D (2002) Reply to the Comment on A Fourier transform EPR study of uracil and thymine radical anions in aqueous solution)/ by DM Close. Phys Chem Chem Phys 4 45 Naumov S, Barthel A, Reinhold J, Dietz F, Geimer J, Beckert D (2000) Calculation of spin densities of radicals of pyrimidine-type bases by density functional theory. Influence of solvent and comparison with EPR results. Phys Chem Chem Phys 2 4207-4211 Naumov S, Hildenbrand K, von Sonntag C (2001) Tautomers of the N-centered radical generated by reaction of SO4 - with N(1)substituted cytosines in aqueous solution. Calculation of isotropic hyperfine coupling constants by a density functional method. J Chem Soc Perkin Trans 2 1648-1653... 

Schwarz values of a turn out to lie between Slater s value of one and the Gaspar-Kohn-Sham (GKS) value of 2/3, as would those of a method constructed to give the total nonrelativistic atomic electronic energy. All values are used in the following spin density-functional expression for the exchange and correlation (XC) energy,... 

A method to calculate J]j, based on the local approximation to spin density functional theory has been developed by Liechtenstein et al. [51, 52]. Using spherical charge and spin densities and a local force theorem, expression for Jjj is... 

Electronic Structure Calculations. We have used first-principles electronic structure calculations as manifest in the (spin) density functional linearized muffin-tin orbital method to examine whether the asymmetry in properties is reflected in a corresponding asymmetry in the one-electron band structure. While in a more complete analysis explicit electron correlation of the Hubbard U type would be intrinsic to the calculation,17 we have taken the view that one-electron bandwidths point to the possible role that correlation might play and that correlation could be a consequence of the one-electron band structure rather than an integral part of the electronic structure. We have chosen the Lai- Ca,Mn03 system for our calculations to avoid complications due to 4f electrons in the corresponding Pr system. 

The cornerstone of the field (the "Hartree-Fock" of Density Functional Theory) is the Local Density Approximation (LDA) also called the Local (Spin) Density (LSD) method Here the basic information on electron correlation, how electrons avoid each other, is taken from the uniform density electron gas Essentially exact calculations exist for this system (the Quantum Monte Carlo work of Ceperley and Alder) and this information from the homogeneous model is folded into the inhomogeneous case through the energy integral ... 

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