Use of atomic fues potential within the floating spherical gaussian orbital method: Study of some two-valence-electron diatomics and triatomic ions

Pramana ◽  
1978 ◽  
Vol 10 (2) ◽  
pp. 201-206 ◽  
Author(s):  
N K Ray ◽  
S P Mehandru
Keyword(s):  
Valence Electron ◽  
Orbital Method ◽  
Gaussian Orbital

The electronic structure of polymers by the FSGO (Floating Spherical Gaussian Orbital) method

1980 ◽  
Vol 57 (1) ◽  
pp. 43-51 ◽  
Author(s):  
David R. Armstrong ◽  
John Jamieson ◽  
Peter G. Perkins
Keyword(s):  
Electronic Structure ◽  
Orbital Method ◽  
Gaussian Orbital

Use of pseudopotentials within the floating spherical Gaussian orbital method: Calculations on methane

1976 ◽  
Vol 65 (11) ◽  
pp. 4467-4469 ◽  
Author(s):  
Sid Topiol ◽  
Arthur A. Frost ◽  
Mark A. Ratner ◽  
Jules W. Moskowitz
Keyword(s):  
Orbital Method ◽  
Gaussian Orbital

Description of a π-system using the floating spherical gaussian orbital method

1995 ◽  
Vol 337 (2) ◽  
pp. 155-160 ◽  
Author(s):  
A.H. Pakiari ◽  
M.H. Keshavarz
Keyword(s):  
Orbital Method ◽  
Gaussian Orbital

DENSITY FUNCTIONAL THEORY ON FLOATING SPHERICAL GAUSSIAN ORBITAL METHOD

2002 ◽  
Vol 13 (08) ◽  
pp. 1095-1103 ◽  
Author(s):  
A. H. PAKIARI ◽  
A. MOHAJERI
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Chemical Species ◽  
Stable Condition ◽  
Point Of View ◽  
Orbital Method ◽  
Functional Theory ◽  
Energy Functionals ◽  
First Time ◽  
Gaussian Orbital

This research is an introduction to density functional theory (DFT), which has been designed for Floating Spherical Gaussian Orbital (FSGO) method for the first time. Our principal objective is to apply a combination of energy functionals to the FSGO densities. The functionals used are separated into exchange and correlation parts. For the exchange part the Becke exchange that includes gradient correction is used. The correlation part has been carried out using Lee, Yang and Parr gradient-corrected functional. Three goals are investigated in this research. Is it possible to apply DFT in the FSGO procedure to obtain the electronic structure of chemical species? Second, is it a stable condition, from the variational point of view, during optimization of exponents and coefficients of each Gaussian? Thirdly, when the two above questions are encouraging, are the results consistent with other results in the literature? In this research we are looking for acceptable answers to the above questions.

Chemical Species Identification in an SEM by Changes in Emitted X-Ray Energies

1974 ◽  
Vol 32 ◽  
pp. 570-571
Author(s):  
R. H. Duff
Keyword(s):  
Species Identification ◽  
Valence Electron ◽  
Chemical Species ◽  
X Rays ◽  
Chemical Bonds ◽  
Small Shift ◽  
X Ray ◽  
Electron Transitions ◽  
Peak Energy ◽  
Chemical Combination

A material irradiated with electrons emits x-rays having energies characteristic of the elements present. Chemical combination between elements results in a small shift of the peak energies of these characteristic x-rays because chemical bonds between different elements have different energies. The energy differences of the characteristic x-rays resulting from valence electron transitions can be used to identify the chemical species present and to obtain information about the chemical bond itself. Although these peak-energy shifts have been well known for a number of years, their use for chemical-species identification in small volumes of material was not realized until the development of the electron microprobe.

Valence electron spectroscopy of inhomogeneous media

1992 ◽  
Vol 50 (2) ◽  
pp. 1150-1151
Author(s):  
A. Howie ◽  
D.W. McComb
Keyword(s):  
Specific Gravity ◽  
Loss Function ◽  
Electron Spectroscopy ◽  
Valence Electron ◽  
Peak Height ◽  
Loss Functions ◽  
Loss Peak ◽  
High Energies ◽  
Valence Electron Density ◽  
Electron Microscopist

The bulk loss function Im(-l/ε (ω)), a well established tool for the interpretation of valence loss spectra, is being progressively adapted to the wide variety of inhomogeneous samples of interest to the electron microscopist. Proportionality between n, the local valence electron density, and ε-1 (Sellmeyer's equation) has sometimes been assumed but may not be valid even in homogeneous samples. Figs. 1 and 2 show the experimentally measured bulk loss functions for three pure silicates of different specific gravity ρ - quartz (ρ = 2.66), coesite (ρ = 2.93) and a zeolite (ρ = 1.79). Clearly, despite the substantial differences in density, the shift of the prominent loss peak is very small and far less than that predicted by scaling e for quartz with Sellmeyer's equation or even the somewhat smaller shift given by the Clausius-Mossotti (CM) relation which assumes proportionality between n (or ρ in this case) and (ε - 1)/(ε + 2). Both theories overestimate the rise in the peak height for coesite and underestimate the increase at high energies.

Valence electron energy loss spectroscopy in reflection geometry

1989 ◽  
Vol 47 ◽  
pp. 378-379
Author(s):  
J. Liu ◽  
J. M. Cowley
Keyword(s):  
Energy Loss ◽  
Valence Electron ◽  
Interband Transition ◽  
Specular Reflection ◽  
Three Dimensional ◽  
Electron Excitation ◽  
Transmission Electron ◽  
Yield Information ◽  
Valence Bands ◽  
Excitation Processes

The low energy loss region of a EELS spectrum carries information about the valence electron excitation processes (e.g., collective excitations for free electron like materials and interband transitions for insulators). The relative intensities and the positions of the interband transition energy loss peaks observed in EELS spectra are determined by the joint density of states (DOS) of the initial and final states of the excitation processes. Thus it is expected that EELS in reflection mode could yield information about the perturbation of the DOS of the conduction and valence bands of the bulk crystals caused by the termination of the three dimensional periodicity at the crystal surfaces. The experiments were performed in a Philipps 400T transmission electron microscope operated at 120 kV. The reflection EELS spectra were obtained by a Gatan 607 EELS spectrometer together with a Tracor data acquisition system and the resolution of the spectrometer was about 0.8 eV. All the reflection spectra are obtained from the specular reflection spots satisfying surface resonance conditions.

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