Theoretical studies of Si vapor-phase epitaxial growth by Iab initioP molecular-orbital calculations

1990 ◽  
Vol 41 (18) ◽  
pp. 12720-12727 ◽  
Author(s):  
Yoshio Ohshita ◽  
Akihiko Ishitani ◽  
Toshikazu Takada
Keyword(s):  
Epitaxial Growth ◽  
Molecular Orbital ◽  
Vapor Phase ◽  
Molecular Orbital Calculations ◽  
Theoretical Studies

Experimental and theoretical estimates of the internal rotational barrier of benzyl fluoride in the vapor phase

1990 ◽  
Vol 68 (4) ◽  
pp. 581-586 ◽  
Author(s):  
Ted Schaefer ◽  
Christian Beaulieu ◽  
Rudy Sebastian ◽  
Glenn H. Penner
Keyword(s):  
Molecular Orbital ◽  
Vapor Phase ◽  
Phenyl Group ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Basis Sets ◽  
Molecular Orbital Calculations ◽  
Stable Conformer ◽  
Spin Coupling Constants ◽  
Spin Spin Coupling

The twofold barrier to rotation about the [Formula: see text] bond in benzyl fluoride is deduced from the long-range 1H,1H; 1H,19F; and 13C,19F nuclear spin–spin coupling constants in solution. The barrier changes from 3.2(2) kJ/mol in the polar solvent, acetonitrile-d3, to 0.7(2) kJ/mol in the nonpolar environment provided by cyclohexane-d12. In all solutions the conformer of greatest stability has the C—F bond in a plane perpendicular to that of the phenyl group. Extrapolation of the barrier to the vapor phase, using a simple reaction field model, indicates that the most stable conformer for the free (unclustered) molecule is now that with the C—F bond in the phenyl plane and that the barrier to internal rotation is 1.1(7) kJ/mol. Molecular orbital calculations with the basis sets STO-3G, 4-21G, 4-31G, 6-31G, and 6-31G* all predict the latter conformer as that of lowest energy. However, they disagree significantly among themselves as to the height of the internal barrier. The complete geometries are given for both conformers, as computed with the 6-31G basis, and the side-chain geometries are tabulated for the planar and perpendicular conformers, as given by all the bases. Keywords: benzyl fluoride, internal rotational potential; 13C,19F spin–spin coupling constants in benzyl fluoride; benzyl fluoride, molecular orbital computations.

Theoretical Studies of Nonbenzenoid Hydrocarbons: 16 π-Electron Systems

1971 ◽  
Vol 49 (17) ◽  
pp. 2840-2849 ◽  
Author(s):  
F. W. Birss ◽  
N. K. Das Gupta
Keyword(s):  
Molecular Orbital ◽  
Molecular Orbital Calculations ◽  
Theoretical Studies ◽  
Electron Systems ◽  
Consistent Field ◽  
Resonance Energies ◽  
Self Consistent ◽  
Self Consistent Field ◽  
Semi Empirical

Hückel and self-consistent-field semi-empirical π-electron molecular orbital calculations on pentalenoheptalene are reported and the results compared to those of pyrene, acepleiadylene, napth[cde]azulene, and cyclohept[bc]acenaphthylene which contain the same number of π electrons. Resonance energies of all molecules calculated by the methods of Dewar and Whitehead are reported. It is suggested that pentalenoheptalene can be treated as two fused azulene nuclei.

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