Ab-initio LCAO-MO-SCF calculations of morphine and nalorphine and measurement of their photoelectron spectra

1976 ◽  
Vol 98 (6) ◽  
pp. 1342-1345 ◽  
Author(s):  
Herbert E. Popkie ◽  
Walter S. Koski ◽  
Joyce J. Kaufman
Keyword(s):  
Ab Initio ◽  
Photoelectron Spectra ◽  
Scf Calculations ◽  
Lcao Mo

Ab Initio LCAO–MO–SCF Calculations on Formic Acid, Formate Ion, and Protonated Formic Acid

1970 ◽  
Vol 52 (4) ◽  
pp. 1784-1789 ◽  
Author(s):  
A. C. Hopkinson ◽  
K. Yates ◽  
I. G. Csizmadia
Keyword(s):  
Formic Acid ◽  
Ab Initio ◽  
Scf Calculations ◽  
Lcao Mo

Photoelectron spectroscopy and ab initio LCAO MO SCF calculations on thiazyl fluoride

1972 ◽  
Vol 14 (4) ◽  
pp. 525-527 ◽  
Author(s):  
R.L. Dekock ◽  
D.R. Lloyd ◽  
A. Breeze ◽  
G.A.D. Collins ◽  
D.W.J. Cruickshank ◽  
...  
Keyword(s):  
Ab Initio ◽  
Photoelectron Spectroscopy ◽  
Scf Calculations ◽  
Lcao Mo

An ab initio and ion cyclotron resonance study of the reactions between alkoxide negative ions and silane systems. Stable adduct formation, and nucleophilic displacement reactions

1981 ◽  
Vol 34 (3) ◽  
pp. 519 ◽  
Author(s):  
G Klass ◽  
VC Trenerry ◽  
JC Sheldon ◽  
JH Bowie
Keyword(s):  
Ab Initio ◽  
Negative Ions ◽  
Ion Cyclotron Resonance ◽  
Trigonal Bipyramidal ◽  
Nucleophilic Displacement ◽  
Stable Adduct ◽  
Displacement Reactions ◽  
Scf Calculations ◽  
Hydrogen Scrambling ◽  
Lcao Mo

Ab initio LCAO-MO-SCF calculations suggest that reaction of HO-(or MeO-) with silane should proceed through a stable trigonal bipyramidal adduct. Reaction of alkoxide anions with a variety of alkylsilanes in an i.c.r. spectrometer leads to (i) nucleophilic displacement reactions, (ii) stable adducts, (iii) decomposing adducts which collapse to tetrahedral anions by elimination of a neutral molecule, and (iv) proton abstraction reactions. The nucleophilic displacement reaction between MeO- and Me3SiR has been used to produce a variety of R- species, including the allyl, propargyl and benzyl anions. The reactions of these ions with methyl nitrite have been used to show that (i) the benzyl anion does not undergo benzylic hydrogen/phenyl hydrogen scrambling prior to reaction, (ii) the allyl anion reacts as a symmetrical species, and (iii) that hydrogen scrambling does not occur in the propargyl anion, and that C3H3- may either react as HC≡C-CH2- or -HC=C=CH2.

The Electronic Structure of Tetraphosphorus-and Tetraarsenic- Trisulphides; Interpretation of their Photoelectron Spectra

1983 ◽  
Vol 38 (1) ◽  
pp. 78-85 ◽  
Author(s):  
Michael H. Palmer ◽  
Robert H. Findlay
Keyword(s):  
Electronic Structure ◽  
Ab Initio ◽  
Configuration Interaction ◽  
Photoelectron Spectrum ◽  
Ground States ◽  
Photoelectron Spectra ◽  
Interaction Studies ◽  
Koopmans Theorem ◽  
Scf Calculations

Abstract Ab initio SCF calculations of the X1A1 ground states of P4S3 and As4S3 are reported, together with configuration interaction studies of the 2 A1, 2 A1, 2 A2 and 2 E states of P4S3. A re-interpretation of the UV-photoelectron spectrum of the P4S3 molecule, and As4S3 by analogy, is presented and it is noted that Koopmans′ theorem yields a very similar order and spacing between groups to the doublet states computed by configuration interaction.

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.

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