中国物理B ›› 2016, Vol. 25 ›› Issue (6): 67105-067105.doi: 10.1088/1674-1056/25/6/067105

• CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES • 上一篇    下一篇

Compton profiles of NiO and TiO2 obtained from first principles GWA spectral function

S M Khidzir, M F M Halid, W A T Wan Abdullah   

  1. Department of Physics, Universiti of Malaya, 50603 Kuala Lumpur, Malaysia
  • 收稿日期:2015-12-22 修回日期:2016-03-04 出版日期:2016-06-05 发布日期:2016-06-05
  • 通讯作者: S M Khidzir E-mail:sidiqmk@gmail.com

Compton profiles of NiO and TiO2 obtained from first principles GWA spectral function

S M Khidzir, M F M Halid, W A T Wan Abdullah   

  1. Department of Physics, Universiti of Malaya, 50603 Kuala Lumpur, Malaysia
  • Received:2015-12-22 Revised:2016-03-04 Online:2016-06-05 Published:2016-06-05
  • Contact: S M Khidzir E-mail:sidiqmk@gmail.com

摘要:

In this work, we first use momentum density studies to understand strongly correlated electron behavior, which is typically seen in transition metal oxides. We observe that correlated electron behavior as seen in bulk NiO is due to the Fermi break located in the middle of overlapping spectral functions obtained from a GW (G is Green's function and W is the screened Coulomb interaction) approximation (GWA) calculation while in the case of TiO2 we can see that the origin of the constant momentum distribution in lower momenta is due to a pile up of spectra before the Fermi energy. These observations are then used to compare our calculated Compton profiles with previous experimental studies of Fukamachi and Limandri. Our calculations for NiO are observed to follow the same trend as the experimental profile but it is seen to have a wide difference in the case of TiO2 before the Fermi break. The ground state momentum densities differ significantly from the quasiparticle momentum density, thus stressing the importance of the quasiparticle wave function as the input for the study of charge density and the electron localization function. Finally we perform a calculation of the quasiparticle renormalization function, giving a quantitative description of the discontinuity of the GWA momentum density.

关键词: elastic and Compton scattering, density functional theory, local density approximation, gradient and other corrections, elements, oxides, nitrides, borides, carbides, chalcogenides

Abstract:

In this work, we first use momentum density studies to understand strongly correlated electron behavior, which is typically seen in transition metal oxides. We observe that correlated electron behavior as seen in bulk NiO is due to the Fermi break located in the middle of overlapping spectral functions obtained from a GW (G is Green's function and W is the screened Coulomb interaction) approximation (GWA) calculation while in the case of TiO2 we can see that the origin of the constant momentum distribution in lower momenta is due to a pile up of spectra before the Fermi energy. These observations are then used to compare our calculated Compton profiles with previous experimental studies of Fukamachi and Limandri. Our calculations for NiO are observed to follow the same trend as the experimental profile but it is seen to have a wide difference in the case of TiO2 before the Fermi break. The ground state momentum densities differ significantly from the quasiparticle momentum density, thus stressing the importance of the quasiparticle wave function as the input for the study of charge density and the electron localization function. Finally we perform a calculation of the quasiparticle renormalization function, giving a quantitative description of the discontinuity of the GWA momentum density.

Key words: elastic and Compton scattering, density functional theory, local density approximation, gradient and other corrections, elements, oxides, nitrides, borides, carbides, chalcogenides

中图分类号:  (Density functional theory, local density approximation, gradient and other corrections)

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77.84.Bw (Elements, oxides, nitrides, borides, carbides, chalcogenides, etc.)