Self-consistent spin-polarized calculations

The calculated Stoner product (Eriksson et al. 1988d) for these compounds predicts URhj and URh2Pd to be paramagnetic and the contrary for URhPdj and UPd3. Self-consistent spin-polarized calculations yielded saturated U-5f moments for concentrations with y > f, which is consistent with localized 5f states, and Eriksson et al. (1988d) argued that y = f might be identified with the critical concentration for localization of the 5f electrons on the uranium atom. 

The muffin-tin potential around each atom in the unit cell has been calculated in the framework of the Local-Spin-Density-Approximation using the ASW method. The ASW method uses the atomic sphere approximation (ASA), i.e. for each atom a sphere radius is chosen such that the sum of the volumes of all the overlapping spheres equals the unit cell volume. The calculation yields the expected ferromagnetic coupling between Cr and Ni. From the self-consistent spin polarized DOS, partial and total magnetic moment per formula unit can be computed. The calculated total magnetic moment is 5.2 pg in agreement with the experimental value (5.3 0.1 e calculations presented here have been performed... 

The LSD calculations of HJ predict a l(Tg2ffg l7r 15g l(5 l7ig lUy ground state with a second state derived by transferring an electron from 5 to Ttg about 0.2 eV higher. The calculated bond length, 2.07 A, is a reasonable interpolant of the experimental values for Ni2 and Fe2 while the calculated frequency, 360 cm S is only in moderate accord with the experimental value. No fully self-consistent spin-polarized LSD calculations have yet been performed for C02. 

The adequacy of the spin-averaged approach has been confirmed in self-consistent spin-density-functional calculations for H in Si by Van de Walle et al. (1989). The deviation from the spin-averaged results is expected to be largest for H at the tetrahedral interstitial (T) site, where the crystal charge density reaches its lowest value. For neutral H at the T site, it was found that inclusion of spin polarization lowered the total energy of the defect only by 0.1 eV. The defect level was split into a spin-up and a spin-down level, which were separated by 0.4 eV. These results are consistent with spin-polarized linearized-muffin-tin-orbital (LMTO) Green s-function calculations (Beeler, 1986). 

In section 2 the theory of ensembles is reviewed. Section 3 summarizes the parameter-free theory of G par[ll]. The self-consistently determined ensemble a parameters of the ensemble Xa potential are presented. In section 4 spin-polarized calculations using several ground-state exchange-correlation potentials are discussed. In section 5 the w dependence of the ensemble a parameters is studied. It is emphasized that the excitation energy can not generally be calculated as a difference of the one-electron energies. The additional term should also be determined. Section 6 presents accurate... 

Pietzsch O, Kubetzka A, Bode M, Wiesendanger R (2001) Observation of magnetie hysteresis at the nanometer scale by spin-polarized scaniung tunneling spectroscopy. Science 292 2053-2056 Pindor AJ, Staunton J, Stocks GM, Winter H (1983) Disordered loci moment state of magnetie transition metals A self-consistent KKR CPA calculation. J Phys F Metal Phys 13 979-989 Politi P, Rettori A, Hartmann-Boutron F, Villain J (1995) Tunneling in mesoscopie magnetie moleeules. Phys Rev Lett 75 537-540... 

The structural similarity of MgAgAs-type compounds with Heusler alloys and with the transition-metal based half-metallic ferromagnets (de Groot et al. 1983) has provoked band-structure calculations of UNiSn (Mueller et al. 1987, Albers et al. 1987). Self-consistent-field scalar relativistic spin-polarized calculations neglecting the spin-orbit coupling revealed the following features of the valence band ... 

For H at T in Ge, Pickett et al. (1979) carried out empirical-pseudopotential supercell calculations. Their band structures showed a H-induced deep donor state more than 6 eV below the valence-band maximum in a non-self-consistent calculation. This binding energy was substantially reduced in a self-consistent calculation. However, lack of convergence and the use of empirical pseudopotentials cast doubt on the quantitative accuracy. More recent calculations (Denteneer et al., 1989b) using ab initio norm-conserving pseudopotentials have shown that H at T in Ge induces a level just below the valence-band maximum, very similar to the situation in Si. The arguments by Pickett et al. that a spin-polarized treatment would be essential (which would introduce a shift in the defect level of up to 0.5 Ry), have already been refuted in Section II.2.d. 

The core electrons of all atoms were treated via ultra-soft pseudo potentials [10,11] with a cut-off of 25 Ry for wave function, and 240 for electronic density. The PBE gradient-corrected exchange-correlation function was used in self-consistent DFT calculations. The geometry optimization was performed using a lxlxl /c-point mesh. Because of the natural paired electron occupancies of the adsorbates, spin polarization effects were not considered to be important and were not treated explicitly in this study. 

In the present calculations, the geometries of the Zn clusters up to Zn were taken from Ref. (39). The larger clusters are assumed to have simple hexagonal symmetry (hex) or hexagonal close-packed synunetry (hep) with the same bond distances as in the bulk (45). We performed self consistent calculations on both neutral and ionized clusters (ASCF) in order to account properly for relaxation energies. In the case of ions the calculations were carried out using the spin polarized approach. 

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