The chemistry of Pyridine, Pyrimidine, and Pyrazine

1956 ◽  
Vol 9 (1) ◽  
pp. 83 ◽  
Author(s):  
RD Brown ◽  
ML Heffernan
Keyword(s):  
Molecular Orbital ◽  
Nitrogen Heterocycles ◽  
Chemical Properties ◽  
Detailed Comparison ◽  
Orbital Method ◽  
Molecular Orbital Method ◽  
Good Agreement

The results of a study of pyridine, pyrimidine, and pyrazine by the molecular- orbital method are reported, and a detailed comparison is made with the chemical properties of these molecules. Good agreement is found, indicating that the present theoretical technique is satisfactory for interpreting and predicting the chemical properties of nitrogen heterocycles.

The 'Variable Electronegativity ' Method. II. Pyrrole

1959 ◽  
Vol 12 (3) ◽  
pp. 319 ◽  
Author(s):  
RD Brown ◽  
ML Heffernan
Keyword(s):  
Dipole Moment ◽  
Molecular Orbital ◽  
Electron System ◽  
Orbital Method ◽  
Molecular Orbital Method ◽  
Consistent Field ◽  
Inductive Effects ◽  
Self Consistent Field ◽  
Negligible Contribution ◽  
Good Agreement

The properties of the π-electron system in pyrrole have been studied by a " variable electronegativity " self-consistent field molecular-orbital method and the results compared with those obtained by the conventional SCF procedure. The π-electron distribution calculated by the conventional SCF procedure cannot be satisfactorily reconciled with the observed dipole moment, but the distribution calculated by the VESCF method leads to a predicted dipole moment in good agreement with observation. Polarization of σ-bonds makes a negligible contribution to the dipole moment.Derivation of the coulomb parameters for the simple H�ckel molecular-orbital method from the VESCF results is considered and the factors responsible for auxiliary inductive effects are discussed. The π-electron ionization potential and the positions of the lowest excited states of pyrrole have been calculated by the VE method.

Theoretical study on the diffusion of gases in hexagonal ice by the molecular orbital method

2003 ◽  
Vol 81 (1-2) ◽  
pp. 251-259 ◽  
Author(s):  
A Hori ◽  
T Hondoh
Keyword(s):  
Molecular Orbital ◽  
Lower Energy ◽  
Theoretical Study ◽  
Orbital Method ◽  
Molecular Orbital Method ◽  
Hexagonal Ice ◽  
Diffusion Constants ◽  
Ice Lattice ◽  
Semi Empirical ◽  
Good Agreement

To estimate the diffusion constants for various gases in ice, the barrier energies during interstitial diffusion are calculated for model ice clusters by the molecular orbital method. For He and Ne, the calculated values for diffusion along the c-axis were 0.11 and 0.26 eV, respectively. These are in good agreement with the experimental results. However, the calculated values for the diffusion of He perpendicular to the c-axis are not in close agreement with the experimental data. The barrier energies for O2, N2, and CH4 were calculated by the semi-empirical molecular orbital method and estimated to be 0.35, 0.47, and 0.75 eV, respectively. The lower energy for O2 in comparison with N2 is attributed to the formation of a quasi chemical bond between the O2 molecule and the ice lattice. The diffusion constants for O2, N2, and CH4 were estimated to be 1.8 x 10–11, 2.5 x 10–12, and 2.0 x 10–14 m2s–1, respectively. PACS Nos.: 31.15Ar, 31.15Ne, 66.30Jt, 66.30Ny

Simulations of Chemical Reactions with the Frozen Domain Formulation of the Fragment Molecular Orbital Method

2015 ◽  
Vol 11 (7) ◽  
pp. 3053-3064 ◽  
Author(s):  
Hiroya Nakata ◽  
Dmitri G. Fedorov ◽  
Takeshi Nagata ◽  
Kazuo Kitaura ◽  
Shinichiro Nakamura
Keyword(s):  
Molecular Orbital ◽  
Chemical Reactions ◽  
Orbital Method ◽  
Molecular Orbital Method ◽  
Fragment Molecular Orbital

Extension of the fragment molecular orbital method to treat large open-shell systems in solution

2015 ◽  
Vol 635 ◽  
pp. 86-92 ◽  
Author(s):  
Hiroya Nakata ◽  
Dmitri G. Fedorov ◽  
Kazuo Kitaura ◽  
Shinichiro Nakamura
Keyword(s):  
Molecular Orbital ◽  
Open Shell ◽  
Orbital Method ◽  
Molecular Orbital Method ◽  
Fragment Molecular Orbital

scholarly journals Molecular Interactions between Estrogen Receptor and Its Ligand Studied by the ab Initio Fragment Molecular Orbital Method

2006 ◽  
Vol 110 (47) ◽  
pp. 24276-24276 ◽  
Author(s):  
Kaori Fukuzawa ◽  
Yuji Mochizuki ◽  
Shigenori Tanaka ◽  
Kazuo Kitaura ◽  
Tatsuya Nakano
Keyword(s):  
Estrogen Receptor ◽  
Ab Initio ◽  
Molecular Orbital ◽  
Molecular Interactions ◽  
Orbital Method ◽  
Molecular Orbital Method ◽  
Fragment Molecular Orbital
Sign in / Sign up

Export Citation Format

Share Document