Analysis of XPS valence band spectra of polymers using a density-functional theory based calculation of model oligomers

1999 ◽  
Vol 37 (1) ◽  
pp. 95-103 ◽  
Author(s):  
S. M�hl ◽  
M. Neumann ◽  
B. Schneider ◽  
V. Schlett ◽  
A. Baalmann
Keyword(s):  
Density Functional Theory ◽  
Valence Band ◽  
Density Functional ◽  
Functional Theory ◽  
Band Spectra

A STUDY ON STRAIN AFFECTING ELECTRONIC STRUCTURE OF WURTZITE ZnO BY FIRST PRINCIPLES

2009 ◽  
Vol 23 (19) ◽  
pp. 2339-2352 ◽  
Author(s):  
LI BIN SHI ◽  
SHUANG CHENG ◽  
RONG BING LI ◽  
LI KANG ◽  
JIAN WEI JIN ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Electronic Structure ◽  
Band Structure ◽  
Valence Band ◽  
Density Of States ◽  
First Principles ◽  
Density Functional ◽  
Functional Theory ◽  
Electron Density Difference ◽  
Different Strains

Density of states and band structure of wurtzite ZnO are calculated by the CASTEP program based on density functional theory and plane-wave pseudopotential method. The calculations are carried out in axial and unaxial strains, respectively. The results of density of states in different strains show that the bottom of the conduction band is always dominated by Zn 4s, and the top of valence band is always dominated by O 2p. The variation of the band gap calculated from band structure is also discussed. In addition, p-d repulsion is used in investigating the variation of the top of the valence band in different strains and the results can be verified by electron density difference.

ELECTRONIC STRUCTURE AND OPTICAL ABSORPTION OF N-DOPED ZnO

2009 ◽  
Vol 23 (27) ◽  
pp. 3243-3251 ◽  
Author(s):  
MEILI GUO ◽  
X. D. ZHANG
Keyword(s):  
Density Functional Theory ◽  
Band Gap ◽  
Valence Band ◽  
Density Functional ◽  
Optical Band Gap ◽  
Optical Transition ◽  
Low Energy ◽  
Functional Theory ◽  
N Doping ◽  
Doped Zno

The plane-wave pseudopotential method, based on density functional theory (DFT), has been used to calculate the electronic and optical properties of pure ZnO and N-doped ZnO . The results of density of states (DOS) indicate that the band gap of N-doped ZnO decreases due to the increase of p states in the valence band. Meanwhile, the results of the imaginary part of dielectric function ε2(ω) reveal that the optical transition between O 2p states in the highest valence band and Zn 4s states in the lowest conduction band shifts to the low energy range due to N doping. The optical band gap of ZnO decreases from 3.2 to 2.2 eV after N doping.

Surface Study of Ni2MnGa(100)

2011 ◽  
Vol 684 ◽  
pp. 215-230 ◽  
Author(s):  
S.W. D'Souza ◽  
R.S. Dhaka ◽  
Abhishek Rai ◽  
M. Maniraj ◽  
J. Nayak ◽  
...  
Keyword(s):  
Valence Band ◽  
Photoelectron Spectroscopy ◽  
Density Functional ◽  
Room Temperature ◽  
Compositional Variation ◽  
Ferromagnetic Shape Memory Alloy ◽  
Functional Theory ◽  
Band Spectra ◽  
Ferromagnetic Shape Memory ◽  
Good Agreement

The (100) surface of Ni2MnGa ferromagnetic shape memory alloy exhibits intrinsic surface property dissimilar to the bulk as well as influence of compositional variation at the surface. It is shown that by sputtering at room temperature and annealing at high temperature, it is possible to obtain a clean, ordered and stoichiometric surface. However, for even higher annealing temperatures, the surface becomes Mn rich. The (100) surface of Ni2MnGa is found to have Mn–Ga termination. A surface reconstruction to p4gm symmetry is observed in the austenite phase, while the expected bulk truncated symmetry at surface is p4mm. For the stoichiometric surface, the XPS valence band is compared with our calculations based on first principles density functional theory and good agreement is obtained. The ultraviolet photoelectron spectroscopy (UPS) valence band spectra depend sensitively on composition varying from Ni rich to Mn rich surfaces. A satellite feature observed in both Ni 2p core-level and valence band spectra is related to the narrow 3d valence band in Ni2MnGa.

Sign in / Sign up

Export Citation Format

Share Document