First-principles Full-potential Augmented Plane Wave Research Articles

First principles study of the relative stability and the electronic properties of GaN

Abstract A theoretical study of structural and electronic properties of the GaN compound is presented using the first-principles full-potential augmented plane wave approach within the generalized gradient approximation (GGA). Results are given for lattice parameters, bulk modulus and its first derivatives in the wurtzite, zinc-blende, rock-salt, CsCl, d-β-tin, Immm, Imm2, Cinnabar, Cmcm, and NiAs structures. The relative stability, phase transitions, band gap energies and densities of state for GaN are also presented. The results of these calculations are compared with the available theoretical and experimental data.

First-principles study of the high-pressure suppression of magnetic moments inCeIn3

We use the first-principles full-potential augmented plane-wave plus local-orbital methods to calculate the electronic structure and hyperfine electric interaction of antiferromagnetic ${\text{CeIn}}_{3}$ compound. In addition to the Perdew-Burke-Ernzerhof (PBE) generalized gradient approximation, a more accurate nonempirical density-functional Wu-Cohen generalized gradient approximation (GGA) for the exchange-correlation energy is implemented in the calculations. Results show an almost linear fall of spin magnetic moments of Ce by increasing the pressure. Cerium $f$ states move away from the Fermi level into the conduction band by imposing the pressure which causes the suppression of the magnetic moment in the vicinity of a critical pressure around 9 GPa. A bow shape increase in electric field gradient at In sites is observed under pressure. While Wu and Cohen-GGA approach leads to a good agreement between the critical pressure and bulk modulus values and their experimental data at ambient pressure, it does not amend the values of the lattice constant and electric field gradient of ${\text{CeIn}}_{3}$, calculated through the standard PBE-GGA.

First-principles calculation of oxygen K-electron energy loss near edge structure ofHfO2

Oxygen K-electron energy loss near edge structures (ELNES) of monoclinic, tetragonal, andcubic HfO2 were calculated by the first-principles full-potential augmented plane wave plus local orbitals(APW+lo) method. By considering the relativistic effect as well as the core-hole effect in thecalculation, the experimental oxygen K ELNES was successfully reproduced. The first,second, third, and fourth peaks originate from oxygen p components hybridized with Hfd-eg,d-t2g, s, and p components, respectively. It was found that the spectral differencesamong the polymorphs are mainly caused by the local structure of the Hf in thecrystal.

Interpretation of the Hume-Rothery electron concentration rule in theT2Zn11(T=Ni, Pd, Co, and Fe)γbrasses based on first-principles FLAPW calculations

The first-principles full-potential augmented plane wave (FLAPW) band calculations were performed for a series of ${T}_{2}{\mathrm{Zn}}_{11}$ ($T=\mathrm{Ni}$, Pd, Co, and Fe) $\ensuremath{\gamma}$ brasses to elucidate the Hume-Rothery electron concentration rule. The pseudogap is found immediately below the Fermi level ${E}_{F}$ in the ${\mathrm{Ni}}_{2}{\mathrm{Zn}}_{11}$ and ${\mathrm{Pd}}_{2}{\mathrm{Zn}}_{11}\phantom{\rule{0.3em}{0ex}}\ensuremath{\gamma}$ brasses. A resulting gain in the electronic energy is attributed to their stabilization in the same way as in ${\mathrm{Cu}}_{5}{\mathrm{Zn}}_{8}$ and ${\mathrm{Cu}}_{9}{\mathrm{Al}}_{4}$ previously studied. However, the pseudogap is essentially shifted above ${E}_{F}$ in both ${\mathrm{Co}}_{2}{\mathrm{Zn}}_{11}$ and ${\mathrm{Fe}}_{2}{\mathrm{Zn}}_{11}$. The Fourier analysis of the FLAPW wave function was made at the symmetry point $N$ of the reduced Brillouin zone in the energy range involving the pseudogap. It is found that the plane wave giving rise to the largest Fourier component always resonates with the {330} and {411} zone planes to produce the pseudogap near ${E}_{F}$. Moreover, a single-branch energy dispersion relation was constructed in the extended zone scheme by averaging the wave vector $2(\mathbf{k}+\mathbf{G})$ having the largest Fourier component of the FLAPW wave function over selected electronic states in the Brillouin zone. The $e∕a$ value thus deduced is found to be close to $21∕13=1.615$ for ${\mathrm{Cu}}_{5}{\mathrm{Zn}}_{8}$, ${\mathrm{Cu}}_{9}{\mathrm{Al}}_{4}$, ${\mathrm{Ni}}_{2}{\mathrm{Zn}}_{11}$, and ${\mathrm{Pd}}_{2}{\mathrm{Zn}}_{11}\phantom{\rule{0.3em}{0ex}}\ensuremath{\gamma}$ brasses but to be only 1.4 and 1.3 for ${\mathrm{Co}}_{2}{\mathrm{Zn}}_{11}$ and ${\mathrm{Fe}}_{2}{\mathrm{Zn}}_{11}$, respectively.