A CNDO/2 Molecular Orbital Study of Shared Tetrahedral Edge Conformations in Olivine-Type Compounds

1979 ◽  
Vol 32 (5) ◽  
pp. 949 ◽  
Author(s):  
TJ McLarnan ◽  
RJ Hill ◽  
GV Gibbs
Keyword(s):  
Detailed Analysis ◽  
Molecular Orbital ◽  
Minimum Energy ◽  
Orbital Energy ◽  
Molecular Orbital Calculations ◽  
Molecular Orbital Study ◽  
The Individual ◽  
Olivine Structure ◽  
Semi Empirical ◽  
Shared Edge

Semi-empirical molecular orbital calculations have been used to study the shortening of tetrahedral shared edges in olivine-type compounds. The shared edge conformation in forsterite was modelled by a cluster of SiO3(OH)Mg3(OH)107- composition, consisting of a silicate tetrahedron sharing edges with three magnesium-containing octahedra. Predicted tetrahedron edge lengths agree well with observed values. Calculations on similar clusters representing shared edge conformations in sinhalite, chrysoberyl, and γ-Na2BeF4 also predict shortening of shared edges with d(X2-X3) < d(X3-X3), (X = O,F), as observed. Calculations on Mg2SiS4 fail to predict shortened shared edges. Detailed analysis of the individual molecular orbital energy terms indicates that the minimum energy configuration is determined by a complex sum of one- and two-centre energies. Distortions due to dimensional misfit of polyhedra in olivine structure space group P bnm appear to have relatively little importance in shortening the shared edges of the tetrahedron.

Semi-empirical Molecular Orbital Energy Levels of the Hexammine and Chloroammine Complexes of Co(IV)

1967 ◽  
Vol 22 (2) ◽  
pp. 170-175 ◽  
Author(s):  
Walter A. Yeranos ◽  
David A. Hasman
Keyword(s):  
Molecular Orbital ◽  
Energy Levels ◽  
Empirical Evaluation ◽  
Wave Functions ◽  
Electronic Transitions ◽  
Orbital Energy ◽  
Molecular Orbital Energy ◽  
The One ◽  
Semi Empirical

Using the recently proposed reciprocal mean for the semi-empirical evaluation of resonance integrals, as well as approximate SCF wave functions for Co3+, the one-electron molecular energy levels of Co (NH3) 3+, Co (NH3) 5Cl2+, and Co (NH3) 4Cl21+ have been redetermined within the WOLFSBERG–HELMHOLZ approximation. The outcome of the study fits remarkably well with the observed electronic transitions in the u.v. spectra of these complexes and prompts different band assignments than previously suggested.

Molecular orbital calculations for sulphur-nitrogen heterocycles. I. The 3-hydroxyisothiazole system

1968 ◽  
Vol 21 (5) ◽  
pp. 1113 ◽  
Author(s):  
JR Christie ◽  
B Selinger
Keyword(s):  
Molecular Orbital ◽  
Perturbation Analysis ◽  
Related Species ◽  
Nitrogen Heterocycles ◽  
Chemical Properties ◽  
Molecular Orbital Calculations ◽  
Semi Empirical ◽  
Scf Calculations

LCAO-SCF calculations of various types have been performed for 3-hydroxy-isothiazole and related species. A perturbation analysis has shown that the values assigned to some of the semi-empirical parameters affect the results to a greater extent than has been supposed. Some of the chemical properties can be rationalized on the basis of these calculations.

Theoretical CD Spectrum Evaluation of the Indolylfulgide Molecules by Using Semi-Empirical Molecular Orbital Calculations

2001 ◽  
Vol 74 (6) ◽  
pp. 1101-1108 ◽  
Author(s):  
Eikoh Ankai ◽  
Kazuhisa Sakakibara ◽  
Soichi Uchida ◽  
Yuki Uchida ◽  
Yayoi Yokoyama ◽  
...  
Keyword(s):  
Molecular Orbital ◽  
Molecular Orbital Calculations ◽  
Cd Spectrum ◽  
Semi Empirical ◽  
Spectrum Evaluation

Molecular Orbital Calculations on Penta Coordinated Ferric Dithiocarbamates Exhibiting Intermediate and Low Spin Ground States

1979 ◽  
Vol 34 (12) ◽  
pp. 1500-1506
Author(s):  
P. Ganguli ◽  
K. M. Hasselbach
Keyword(s):  
Energy Level ◽  
Molecular Orbital ◽  
Ground State ◽  
Ground States ◽  
Orbital Energy ◽  
Iron Nucleus ◽  
Molecular Orbital Calculations ◽  
Valence Shell ◽  
Molecular Orbital Energy ◽  
Orbital Energy Level

Abstract SCCEHMO calculations show that the ground state in [Fe(dtc)2X], X = Cl, Br, I and NCS, is 4A2: (x2 - y2)2(xz)1(yz)1(z2)1(xy)0 and for X = NO is 2A1: (xz)2(yz)2(x2-y2)2(z2)1(xy)0. The calculated quadrupole splittings of iron and iodine included the valence shell, overlap charge, and the ligand and lattice contributions to the EFG tensor at the nuclei. In addition, the elec-tron densities at the iron nucleus are compared with the measured isomer shifts. The spin densi-ties may be interpreted in terms of a π-delocalization. The results are discussed on the basis of the molecular orbital energy level schemes.

Sign in / Sign up

Export Citation Format

Share Document