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Title:The electronic momentum distribution of lithium
Author(s):Yang, Yubo
Abstract:This image shows the distribution of the momenta of electrons in crystalline lithium. If electrons were Classical distinguishable particles, then their momentum distribution would start highest at zero momentum (center of image) and decrease smoothly at higher momenta. Instead, we see a near-constant distribution inside the solid bright sphere, and a precipitous drop at its surface. This is known as the Fermi surface or Fermi break. Its existence is evidence for the quantum and fermionic nature of electrons. The “cups” surrounding the Fermi sphere belong to secondary Fermi surfaces. These are created as electrons “bounce off” the crystal lattice. Further out, the more subtle ripples are created by electron-electron correlation. All these features can be probed by Compton scattering experiments. This momentum distribution was calculated using diffusion Monte Carlo (DMC), a numerical technique for solving the Schrödinger equation involving many correlated electrons. Using this data, we helped our experimental colleagues explain the microscopic mechanism for the change of their measured Compton profile from the solid to liquid state. We furthered aided them in extracting the magnitude of the Fermi break from experimental data. This work is available on arXiv: 1912.12295.
Issue Date:2020
Rights Information:Copyright 2020 Yubo Yang
Date Available in IDEALS:2020-04-15

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