The linearized-augmented-plane-wave (LAPW) method for thin films is generalized by removing the remaining shape approximation to potential inside atomic spheres. A new technique solving Poisson's equation a general charge density and described implemented in film LAPW method. In resulting full-potential (FLAPW), all contributions are completely taken into account Hamiltonian matrix elements. accuracy of method---already well known clean metal surfaces---is demonstrated case nearly free...

Phonon frequencies and eigenvectors have been computed from first principles for the three optic ${\mathit{F}}_{1\mathit{u}}$ modes in ${\mathrm{BaTiO}}_{3}$ using full-potential linearized-augmented-plane-wave method. We find that ferroelectric instability can be understood calculations a perfect crystal with periodic boundary conditions. The energy wells soft-mode distortion are deeper rhombohedral [111] displacements relative to tetragonal [001] displacements, but they relatively shallow...

Local-density-functional total-energy calculations are reported for both the structural and metallization transitions of BaSe BaTe. Good agreement with recent experimental results BaTe confirms band-overlap mechanism in this related closed-shell systems. A pressure about 400 kbar is predicted BaSe. These represent first convincing demonstration ability local-density-functional approximation to predict accurately.

Using the total-energy general-potential linearized-augmented-plane-wave method, we have tested adequacy of local-spin-density approximation for describing magnetic and structural properties iron. We find that there are fundamental deficiencies in approximation, both quantitative qualitative, substantial errors calculated ground-state volumes moments, as well a prediction wrong crystal structure.

Electronic energy bands calculated from local-density-functional (LDF) theory are used to predict anisotropic transport properties of the oxide superconductors ${\mathrm{La}}_{2\mathrm{\ensuremath{-}}\mathrm{x}}$${\mathrm{Sr}}_{\mathrm{x}}$${\mathrm{CuO}}_{4}$ and ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7}$. Calculations magnitude resistivity tensor ${\ensuremath{\rho}}_{\ensuremath{\alpha}\ensuremath{\beta}}$ (assuming only electron-phonon scattering) lead results smaller than...

Abstract We have performed extensive self-consistent total energy calculations for PbTiO3 and BaTiO3 in order to better understand the origin of ferroelectric instability perovskites reasons different behavior two materials. Physically reasonable instabilities are found both materials at experimental volume. However, results quite sensitive volume typical local density approximation (LDA) errors can lead significant potential surface distortions. The sensitivity perovskite ferroelectrics...

We present a new method for treating the electronic structure of thin films which is based on generalization bulk linearized augmented-plane-wave (LAPW) method. This avoids using slab-superlattice geometry and combines advantages energy-independent muffin-tin Hamiltonian methods [fast root evaluation rapid convergence $d$-band metals as well nearly-free-electron (NFE) crystals] with simple matrix element determination original augmented plane-wave (APW) As in LAPW method, asymptote problem...

All-electron and pseudopotential formulations for atomic forces in the linear-augmented-plane-wave (LAPW) method within local-density approximation are presented. Due to fact that basis functions LAPW (and other linear muffin-tin-orbitals-based methods) have discontinuous second derivatives across muffin-tin sphere boundaries, a large surface contribution incomplete-basis-set corrections Hellmann-Feynman force is shown exist. The applied frozen-phonon calculations semiconductor,...

The electronic structure of the new Bi-based high-temperature superconductor, with ${T}_{c}$ onsets above 110 K, is shown to be altered considerably from that other cuprate superconductors by presence Bi. There are Bi-O bands which cross Fermi level, and two-dimensional character even greater than previous cuprates. Like cuprates, band critical points occur at level.

We develop a quantum Monte Carlo method for many fermions that allows the use of any one-particle basis. It projects out ground state by random walks in space Slater determinants. An approximate approach is formulated to control phase problem with trial wave function $|\Psi_T>$. Using plane-wave basis and non-local pseudopotentials, we apply Si atom, dimer, 2, 16, 54 atom (216 electrons) bulk supercells. Single determinant functions from density functional theory calculations were used as...

Large nonlocal contributions to the electron-phonon interaction in ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7}$ are found using linearized-augmented-plane-wave method with frozen-phonon technique. These effects greatly increase coupling strength and lower expected isotope effect for oxygen by increasing of heavy ions. We find large anharmonicity chain-oxygen motions, which can also enhance superconducting transition temperature decrease effect. Excellent overall agreement...

Surface states (SS) and surface resonances (SR) on the W(001) have been determined from first self-consistent energy-band study of this metal surface. The calculations were performed for a seven-layer film using our thin-film linearized augmented-plane-wave method which includes all relativistic corrections except spin-orbit interaction. Self-consistency was found to be essential obtaining an accurate value work function-4.5\ifmmode\pm\else\textpm\fi{}0.2 eV, in excellent agreement with...

The first self-consistent computations of piezoelectricity in a ferroelectric are presented. Bulk spontaneous polarization, dynamical charges ( ${Z}^{*}$), and the full piezoelectric stress tensor ${\mathrm{PbTiO}}_{3}$ were determined from ground-state Berry's phase calculations using all-electron linearized augmented plane wave method. Both proper total moduli computed found to be significantly different. theoretical moduli,...

Recent experimental results are beginning to limit seriously the theories that can be considered explain high-temperature superconductivity. The unmistakable observations of a Fermi surface, by several groups and methods, make it focus realistic metallic phases. Data from angle-resolved photoemission, positron annihilaton, de Haas-van Alphen experiments in agreement with band theory predictions, implying phases cannot pictured as doped insulators. character low energy excitations...

With the appearance of angle-resolved photoemission data allowing identification and measurement Fermi surface high-${\mathit{T}}_{\mathit{c}}$ cuprate superconductors, it is important to have precise local-density calculations with which compare. We present well-converged predictions band structure ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7}$, giving special attention position flat Cu-O chain-derived bands effect buckling chain that predicted by total-energy has been inferred...

We present the results of high-precision, all-electron, self-consistent local-spin-density-functional calculations on a seven-layer Ni(001) film using full-potential linearized-augmented-plane-wave method. It is found that surface atoms have magnetic moment which enhanced by almost 20% compared with bulklike in interior film. There no indication Friedel-type oscillation layer-by-layer moments. Although negative core-contact spin densities for are magnitude 20%, contribution from (4s-derived)...

Unlike ${\mathrm{La}}_{2\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Sr}}_{\mathit{x}}$${\mathrm{CuO}}_{4}$, ${\mathrm{La}}_{2\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Ba}}_{\mathit{x}}$${\mathrm{CuO}}_{4}$, x\ensuremath{\sim}${\mathit{x}}_{\mathrm{cr}}$=0.12, undergoes a structural change to low-temperature tetragonal (LTT) phase below 60 K, and this transformation is known suppress ${\mathit{T}}_{\mathit{c}}$ drastically. We present self-consistent local-density-functional calculations...

We present full‐potential self‐consistent linearized augmented plane wave (LAPW) calculations for the electronic structure and total energy of MgO CaO, within local density approximation. Calculated equilibrium properties are in good agreement with experiment. also consider transition from low‐pressure sodium chloride (B1) to high‐pressure cesium (B2) CaO NiAs (B8) structures MgO. In calcium oxide we find that B1‐B2 occurs at 54 GPa, magnesium a B1 B2 is found 510 GPa. This factor 2 lower...

The anisotropic resistivity ${\ensuremath{\rho}}_{\ensuremath{\alpha}\ensuremath{\alpha}}$ and Hall coefficient ${R}_{\ensuremath{\alpha}\ensuremath{\beta}\ensuremath{\gamma}}$ of ${\mathrm{La}}_{2\ensuremath{-}x}{M}_{x}\mathrm{Cu}{\mathrm{O}}_{4}$ are analyzed as a function $x$, using rigid-band treatment the previously given linearized augmented planewave bands tetragonal ${\mathrm{La}}_{2}$Cu${\mathrm{O}}_{4}$. experimental ${\ensuremath{\rho}}_{\mathrm{xx}}(T)$ is used to extract...

The layered structure dichalcogenide Ti${\mathrm{S}}_{2}$ was studied in thin-film and bulk models, with the use of self-consistent linearized augmented-plane-wave (LAPW) scheme. Band-structure calculations were performed on single sandwich (S-Ti-S), double ${(\mathrm{S}\ensuremath{-}\mathrm{T}\mathrm{i}\ensuremath{-}\mathrm{S})}_{2}$, to reveal strength effect interlayer interactions electronic structure. Comparisons are made existing band models. fully intercalated LiTi${\mathrm{S}}_{2}$...

Densities of states and spectral functions are obtained for large (\ensuremath{\sim}8000 atoms) three-dimensional alloy models with cell localized disorder compared the single-site coherent-potential approximation (CPA). We find that CPA agrees remarkably well exact numerical results. In particular, overall structure electronic spectrum transition from one- to two-band behavior described. There is, however, some substructure which is not reproduced by approximation.

Full-potential calculations of the electronic structure and ground-state properties iron using Langreth-Mehl-Hu, Perdew-Wang, Becke gradient-corrected local-density functionals are reported. As in earlier linear-muffin-tin-orbital atomic-spheres approximation, a ferromagnetic bcc ground state is found, although there differences energetics. The effect gradient corrections on discussed detail. It found that significant changes exchange splittings result from nonspherical terms potential,...

Full potential, linearized, augmented plane wave, total-energy calculations predict that the breathing mode in ${\mathrm{La}}_{2}$Cu${\mathrm{O}}_{4}$ is a high-frequency mode, agreement with experiment and contrary to previously published results. We also find experimentally observed tilt be unstable within local-density approximation. Eight other modes were studied, excellent was found, indicating approximation gives accurate total energies static density response for high-temperature...

A complete mapping in the Brillouin zone of structural instability associated with ferroelectric phase transitions ${\mathrm{KNbO}}_{3}$ has been obtained by first-principles calculations using a linear response approach. The wave-vector dependence reveals pronounced two-dimensional character, which corresponds to chains oriented along $〈100〉$ directions displaced Nb atoms. results are discussed relation models transitions.