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

• Published in: Chinese physics B 2016-06, Vol.25 (6), p.407-415
• Main Authors: Khidzir, S M, Halid, M F M, Wan Abdullah, W A T
• Format: Article
• Language: English
• Subjects: borides; carbides; chalcogenides; density functional theory; elastic and Compton scattering; elements; gradient and other corrections; Green函数; local density approximation; NiO; nitrides; oxides; TiO2; 型材; 康普顿; 第一性原理; 谱函数; 过渡金属氧化物
• ISSN: 1674-1056; 2058-3834
• DOI: 10.1088/1674-1056/25/6/067105

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.