The Photoelectron Spectra the Chloro Toluenes

1987 ◽  
Vol 40 (4) ◽  
pp. 751 ◽  
Author(s):  
JB Peel ◽  
EI Vonnagyfelsobuki
Keyword(s):  
Ab Initio ◽  
Cross Section ◽  
Valence Electron ◽  
Model Potential ◽  
Ionization Potentials ◽  
Photoelectron Spectra ◽  
Molecule Model ◽  
Linear Correlations ◽  
Spectral Assignment

The HeI and HeII photoelectron spectra of the chloro toluenes have been measured. The spectra are assigned using HeI/HeII cross-section ratios and a composite-molecule model within an ab initio valence-electron-only model potential (VEOMP) framework. The order of the first two ionization potentials for the chloro toluenes is assigned as πS < πA which is contrary to the VEOMP assignment for benzal chloride and benzotrichloride , but is consistent with linear correlations using group electronegativities and σI scales. Furthermore, linear correlations using the first two ionization potentials of fluoro and chloro toluenes with group electronegativities are shown to be a useful aid in spectral assignment and, moreover, suggest that for benzyl fluoride and benzal chloride the most appropriate σI values are 0.20 and 0.31 respectively.

Variational thermodynamic calculations for some liquid sd metals

1986 ◽  
Vol 64 (1) ◽  
pp. 75-83 ◽  
Author(s):  
D. H. Li ◽  
R. A. Moore ◽  
S. Wang
Keyword(s):  
Ab Initio ◽  
Valence Electron ◽  
Helmholtz Free Energy ◽  
Liquid Metals ◽  
Model Potential ◽  
Variational Calculation ◽  
Hard Sphere Model ◽  
Sphere Model ◽  
Pair Potentials ◽  
The One

A tractable and reliable expression for the one valence-electron eigenenergies, required in calculating the total energy of a disordered sd-type metal, is formulated in the context of the model-potential theory. With the aid of this expression, the variational calculation of the Helmholtz free energy using the hard-sphere model as a reference system, as employed in ab initio calculations of the thermodynamic properties for the nearly-free-electron-like (NFE) liquid metals, can now be extended with reasonable accuracy to those liquid sd metals in which the d-like valence-electron states below the Fermi level are not very localized. Also, the ab initio-type pseudopotential calculation of the interionic pair potentials, as carried out for the NFE-like metals in the literature, is made practical for these sd metals in their disordered states.

scholarly journals Pseudopotential Calculations for Li2, Na2 and NaLi

1988 ◽  
Vol 41 (4) ◽  
pp. 563 ◽  
Author(s):  
N Andriopoulos ◽  
EI von Nagy-Felsobuki
Keyword(s):  
Potential Energy ◽  
Ab Initio ◽  
Electronic State ◽  
Valence Electron ◽  
Large Range ◽  
Model Potential ◽  
Potential Energy Curves ◽  
Basis Sets ◽  
Valence Orbital ◽  
Pseudopotential Calculations

A valence-electron only model potential (V ALMOP) pseudopotential method has been developed utilising the GAUSSIAN 76 integral packages. VALMOP and the reference ab initio potential energy curves have been calculated for the ground electronic state of Li2, Na2 and NaLi using a number of different basis sets. Comparisons indicate that V ALMOP accurately reproduces internuclear bondlengths, valence orbital eigenvalues and, moreover, the shape of the all-electron potential energy curves over a large range of bondlength R.

Gas-Phase Tautomerism in the Triazoles and Tetrazoles: A Study by Photoelectron Spectroscopy and ab Initio Molecular Orbital Calculations

1981 ◽  
Vol 36 (11) ◽  
pp. 1246-1252 ◽  
Author(s):  
Michael H. Palmer ◽  
Isobel Simpson ◽  
J. Ross Wheeler
Keyword(s):  
Ab Initio ◽  
Gas Phase ◽  
Molecular Orbital ◽  
Photoelectron Spectroscopy ◽  
Relative Stability ◽  
Photoelectron Spectra ◽  
Equilibrium Geometry ◽  
Molecular Orbital Calculations ◽  
Methyl Derivatives

The photoelectron spectra of the tautomeric 1,2,3,- and 1,2,4-triazole and 1,2,3,4-tetrazole systems have been compared with the corresponding N-methyl derivatives. The dominant tautomers in the gas phase have been identified as 2 H-1,2,3-triazole, 1 H-1,2,4-triazole and 2H-tetrazole.Full optimisation of the equilibrium geometry by ab initio molecular orbital methods leads to the same conclusions, for relative stability of the tautomers in each of the triazoles, but the calculations wrongly predict the tetrazole tautomerism.

VUV FRAGMENTATION OF SOME HYDROFLUOROCARBON CATIONS STUDIED USING COINCIDENCE TECHNIQUES

2002 ◽  
Vol 09 (01) ◽  
pp. 153-158 ◽  
Author(s):  
WEIDONG ZHOU ◽  
D. P. SECCOMBE ◽  
R. Y. L. CHIM ◽  
R. P. TUCKETT
Keyword(s):  
Kinetic Energy ◽  
Ab Initio ◽  
Ground State ◽  
Lower Energy ◽  
Lone Pair ◽  
Electronic States ◽  
Photoelectron Spectra ◽  
Highest Occupied Molecular Orbital ◽  
Impulsive Model ◽  
Lone Pair Electrons

Threshold photoelectron–photoion coincidence (TPEPICO) spectroscopy has been used to investigate the decay dynamics of the valence electronic states of the parent cation of several hydrofluorocarbons (HFC), based on fluorine-substituted ethane, in the energy range 11–25 eV. We present data for CF 3– CHF 2, CF 3– CH 2 F , CF 3– CH 3 and CHF 2– CH 3. The threshold photoelectron spectra (TPES) of these molecules show a common feature of a broad, relatively weak ground state, associated with electron removal from the highest-occupied molecular orbital (HOMO) having mainly C–C σ-bonding character. Adiabatic and vertical ionisation energies for the HOMO of the four HFCs are presented, together with corresponding values from ab initio calculations. For those lower-energy molecular orbitals associated with non-bonding fluorine 2pπ lone pair electrons, these electronic states of the HFC cation decay impulsively by C–F bond fission with considerable release of translational kinetic energy. Appearance energies are presented for formation of the daughter cation formed by such a process (e.g. CF 3– CHF +), together with ab initio energies of the corresponding dissociation channel (e.g. CF 3– CHF + + F ). Values for the translational kinetic energy released are compared with the predictions of a pure-impulsive model.

Photoelectron spectra of and ab initio calculations on chlorobenzenes. 3. Hexachlorobenzene

1981 ◽  
Vol 85 (11) ◽  
pp. 1495-1497 ◽  
Author(s):  
Branko Ruscic ◽  
Leo Klasinc ◽  
Andreas Wolf ◽  
Jan V. Knop
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Photoelectron Spectra

A Discussion on photoelectron spectroscopy - Orderings of π and σ ionization potentials in carbocyclic and heterocyclic aromatic compounds

1970 ◽  
Vol 268 (1184) ◽  
pp. 131-140 ◽  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Aromatic Compounds ◽  
Lone Pair ◽  
Ionization Potentials ◽  
Photoelectron Spectra ◽  
Light Sources ◽  
Orbital Energies ◽  
Substituted Pyridines ◽  
Nitrogen Lone Pair ◽  
Electron Correlation Effects

Data on calculated orbital energies and experimentally measured ionization potentials of carbocyclic and heterocyclic aromatic compounds are compared and contrasted. The ordering or orbital energies and ionization potentials do not always seem to parallel one another, probably owing to either electron correlation effects, or to deviations from Koopman’s theorem. The effects on photoelectron spectra of using different light sources and analysers are discussed in relation to their bearing on the orbital orderings of aromatic compounds. The high resolution He 584 A. photoelectron spectrum of pyridine is shown to be open to two interpretations regarding the ordering of the ionization potentials of the π orbitals and the ‘nitrogen lone pair’ (n). One of the interpretations involves the three lowest pyridine ionization potentials being π (9.2 eV), π L (9.5 eV) and n (10.5 eV) whilst the other has the first three ionization potentials being the order π , n, π . The photoelectron spectra of substituted pyridines and diazines are discussed in the light of the two possible explanations for the pyridine spectrum.

scholarly journals The ab initio model potential method with the spin-free relativistic scheme by eliminating small components Hamiltonian

2001 ◽  
Vol 114 (14) ◽  
pp. 6000-6006 ◽  
Author(s):  
Kyosuke Motegi ◽  
Takahito Nakajima ◽  
Kimihiko Hirao ◽  
Luis Seijo
Keyword(s):  
Ab Initio ◽  
Potential Method ◽  
Model Potential
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