Electron charge density and electron momentum distribution in magnesium oxide

Causa, Mariella; Dovesi, Roberto; Pisani, Cesare; Roetti, C.

doi:10.1107/s0108768186098270

Cited by 26 publications

(9 citation statements)

References 17 publications

(28 reference statements)

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“…In addition, the coupling of the size of the oxygen ion to the Madelung potential provides a many-body force which produces a Cauchy violation [Mehl et al, 1986]. More recently, Causa et al [1986b] found that Hartree-Fock charge densities for MgO were in good agreement with the ionic model with Note that there is no hybridization between any of the oxygen states and states on the magnesium. For the B2 structure, the gap is indirect from M to F at low pressures and becomes direct at M at high pressures.…”

Section: Equation Of State and High-pressure Propertiesmentioning

confidence: 98%

Linearized augmented plane wave electronic structure calculations for MgO and CaO

Mehl¹,

Cohen²,

Krakauer³

1988

J. Geophys. Res.

160

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Figure 1 lb is not correct. The band structure calculations used to create this figure included so-called "ghost states," spurious wave functions which occasionally appear in linearized methods due to the incompleteness of the basis set. A proper choice of energy parameters will eliminate these states. The self-consistent calculations did not contain ghost states. We have eliminated the ghost states in the calculations leading to the new Figure l lb presented here. The conclusions reached in the paper are actually strengthened. We have also changed Figure 1 la by including the Mg 2p semicore states. Finally, the references to Pickett [1985] and Pickett [1986] should be to the journal Comments on Solid State Physics. We would like to thank H. Lu for doing the calculations for the new Figure 11. a V=18.1A :• b V=lO,&, 3 >'8 o• Madelung Potential,• I _ Modelung Pofenfiol •,"""" .. Watson Potential Watson Potential Fig. 11. Differences in eigenvalues at the F, L, X, and K symmetry points for PIB and LAPW charge densities for the B1 phase of MgO. The curves with solid lines are the O 2p states, the dashed curves are the Mg 2p and O 2s states, and the dotted curves are the excited states. The Madelung potentials are indicated by arrows. (a) 18.1 ,•3, 0 GPa. The best fit Watson sphere potential is very close to the Madelung potential. (b) 10 ,•3, 345 GPa. The best Watson sphere potential is somewhat larger than that given by the Madelung potential, but properly chosen spherical ions give an accurate fit.

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Section: Equation Of State and High-pressure Propertiesmentioning

confidence: 98%

Linearized augmented plane wave electronic structure calculations for MgO and CaO

Mehl¹,

Cohen²,

Krakauer³

1988

J. Geophys. Res.

160

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“…This effect becomes especially prominent for the nearcutoff harmonics. The angular width of the maxima along the Mg-O bonding direction is ∼10 • , which approximates the angle subtended by the O atom to the Mg atom considering their atomic radii 19 .…”

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confidence: 99%

Anisotropic high-harmonic generation in bulk crystals

2016

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The microscopic valence electron density determines the optical, electronic, structural and thermal properties of materials. However, current techniques for measuring this electron charge density are limited: for example, scanning tunnelling microscopy is confined to investigations at the surface, and electron di raction requires very thin samples to avoid multiple scattering 1 . Therefore, an optical method is desirable for measuring the valence charge density of bulk materials. Since the discovery of high-harmonic generation (HHG) in solids 2 , there has been growing interest in using HHG to probe the electronic structure of solids 3-11 . Here, using single-crystal MgO, we demonstrate that high-harmonic generation in solids is sensitive to interatomic bonding. We find that harmonic e ciency is enhanced (diminished) for semi-classical electron trajectories that connect (avoid) neighbouring atomic sites in the crystal. These results indicate the possibility of using materials' own electrons for retrieving the interatomic potential and thus the valence electron density, and perhaps even wavefunctions, in an all-optical setting.High-harmonic generation (HHG) in bulk crystal is attributed to the sub-cycle electronic motion driven by an intense laser field [2][3][4][5][6][7][8][9][10][11] . There has been a growing interest in utilizing HHG to probe the electronic structure of solids 8,9,11 . Vampa et al. reconstructed the momentum-dependent bandgap of ZnO along the -M direction using HHG from a two-colour driving field 11 . Luu et al. retrieved the energy dispersion of the lowest conduction band of SiO 2 assuming that the harmonics are produced by the intraband currents 8 . The dependence of solid-state HHG on the coupling of multiple electronic bands has also been identified with the production of even harmonics in GaSe 9 and the emergence of a second plateau in rare-gas solids 12 . These findings show the possibility of using solidstate HHG to probe the electronic band structures in solids, but the analyses are so far limited to one dimension. For a complete electronic structure, it is desirable to exploit the microscopic process to measure the periodic potential in three dimensions (real space). This is analogous to tomographic imaging of a molecule, where the three-dimensional spatial information (that is, orbital wavefunction) of the target molecule is extracted [13][14][15] . Those measurement techniques are based critically on the dependence of HHG efficiency on molecular alignment with respect to the laser field 16 .In this letter, we demonstrate the strong sensitivity of HHG to the atomic-scale structure in the cubic wide-bandgap crystal MgO. First, using a linearly polarized field, we measure a highly anisotropic angular distribution in high-harmonic signal-despite the isotropic linear and weakly anisotropic nonlinear optical properties of the cubic crystal in the perturbative regime 17 . Second, we observe a strong ellipticity dependence of the HHG yield similar to the gas-phase HHG 18 for small elliptic...

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“…In order to clarify electronic and chemical properties of the average structure we determined the valence-electron density distribution using the density-functional theory (DFT hereafter) formalism (Hohenberg & Kohn, 1964;Kohn & Sham, 1965). It is an established fact that the electron density distribution determined by ab initio approaches such as Hartree±Fock calculations (Causa et al, 1986) or DFT (Charlier et al, 1991) fall within the experimental error bar of X-ray determinations. In a complementary study of the average structure of calaverite (Gonze et al, 2001) we determined the equilibrium geometry within the DFT.…”

Section: Introductionmentioning

confidence: 81%

Ab initio determination of the valence electron distribution in the average structure of the incommensurately modulated calaverite AuTe₂

Caracas

Gonze

2001

Acta Crystallogr Sect B

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The valence-electron density distribution of the average structure of incommensurately modulated calaverite, AuTe 2 , has been computed using density-functional theory. Highdensity regions, centered around the Au and Te atoms, are not spheric, but present charge concentrations along the AuÐTe and TeÐTe bonds. The electronic band structure and its corresponding density of states reveal the presence of three electronic band groups, constituted mainly by Te 5s, Au 5d and hybrids of Te 6p + Au 6s + Au 5d orbitals. The electrons belonging to the last block are responsible for the chemical bonds.

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Electron charge density and electron momentum distribution in magnesium oxide

Cited by 26 publications

References 17 publications

Linearized augmented plane wave electronic structure calculations for MgO and CaO

Linearized augmented plane wave electronic structure calculations for MgO and CaO

Anisotropic high-harmonic generation in bulk crystals

Ab initio determination of the valence electron distribution in the average structure of the incommensurately modulated calaverite AuTe₂

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Electron charge density and electron momentum distribution in magnesium oxide

Cited by 26 publications

References 17 publications

Linearized augmented plane wave electronic structure calculations for MgO and CaO

Linearized augmented plane wave electronic structure calculations for MgO and CaO

Anisotropic high-harmonic generation in bulk crystals

Ab initio determination of the valence electron distribution in the average structure of the incommensurately modulated calaverite AuTe2

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Ab initio determination of the valence electron distribution in the average structure of the incommensurately modulated calaverite AuTe₂