Influence of lattice dynamics on electron momentum density of lithium

Anharmonic Thermal Oscillations of the Electron Momentum Distribution in Lithium Fluoride

“…In the upper panel of Fig. 3, we report our experimentally measured difference of the directional J 110 ðpÞ CP of LiF between 300 and 10 K, which shows clear oscillations almost up to jpj ¼ 4 a:u: Previous high-resolution experimental measurements of thermal effects on CPs revealed such oscillations on simple metals: empirical calculations supported the picture according to which the large oscillations at small momenta, jpj < jp F j, were mainly due to thermal expansion while the small oscillations at higher momenta (when detected) to thermal disorder [22][23][24]. Along with experimental measurements, the upper panel of Fig.…”

“…and were unable to confirm this picture and measured an opposite effect: a narrowing of the CP upon heating [21][22][23]. In particular, Sternemann and co-workers, by means of empirical temperature-dependent local pseudopotential computations, suggested lattice expansion (i.e., the Fermi momentum p F change with temperature) to be the dominant effect on the thermal response of the EMD of several simple metals for jpj ≤ jp F j.…”

“…In particular, Sternemann and co-workers, by means of empirical temperature-dependent local pseudopotential computations, suggested lattice expansion (i.e., the Fermi momentum p F change with temperature) to be the dominant effect on the thermal response of the EMD of several simple metals for jpj ≤ jp F j. In the case of lithium, where higher momentum components (HMC) to the valence EMD of the system show a nonzero dependence on temperature, the need for an explicit treatment of thermal disorder (by means of Debye-Waller factors, for instance) was invoked for jpj > jp F j [22][23][24].…”

Reconstructed three-dimensional electron momentum density in lithium: A Compton scattering study

“…Consistent with several recent studies, 4-12 these discrepancies between theory and experiment reflect the effects of electron correlations ͑beyond the present LDA theory͒ which shift spectral weight from below to above the Fermi momentum and reduce the size of the break Z k at the Fermi momentum. 53,54 Reference 5 adduced a nearly zero value of Z k in Li from an analysis of their CP data. Although our conclusions in this regard are qualitatively similar to those of Ref.…”

Pressure-induced transitions in solid nitrogen: Role of dispersive interactions

“…An interesting approach was proposed by Dugdale and Jarlborg for describing nuclear motion effects on the CP of alkali metals: 70 for this purpose they used a statistically averaged CP coming from a number of supercell calculations, each describing a thermally disordered distribution of the nuclear positions; electron correlation was accounted for by means of a modified Fermi distribution of level occupation. A different scheme was tried by Sternemann et al for interpreting the change in the [110] CP of lithium when passing from 95 to 295 K; 71 the experimental results were in good agreement with LDA calculations, where an empirical pseudopotential was introduced, simulating on average thermal disorder; the experimental change in the lattice constant with temperature was also accounted for. It can be noted incidentally that, according to the latter scheme, the nodal condition [Eq.…”