Intramolecular interactions in N-methylsalicylaldimine and its anion. A semi-empirical energy partitioning analysis

1981 ◽  
Vol 78 ◽  
pp. 127-130 ◽  
Author(s):  
Salavatore Millefiori ◽  
Arcangelo Millefiori
Keyword(s):  
Energy Partitioning ◽  
Intramolecular Interactions ◽  
Semi Empirical

Selfconsistent Optimization of Molecular Geometries by Semi-empirical Force Field MethodII. Relaxational Effects Accompanying Torsion in Formamide

1977 ◽  
Vol 32 (3-4) ◽  
pp. 276-284
Author(s):  
Roman F. Nalewajski
Keyword(s):  
Force Field ◽  
Geometry Optimization ◽  
Energy Partitioning ◽  
Strongly Coupled ◽  
Relaxation Effects ◽  
Empirical Force Field ◽  
Large Application ◽  
Semi Empirical ◽  
Equilibrium Geometries ◽  
Good Agreement

Abstract The geometry relaxation effects accompanying the internal rotation in formamide are investigated using the selfconsistent MINDO force field procedure 1. The results of test calculations of H2O2 are also briefly summarized. The relaxation appears to be necessary for the barrier to the NH2 in­ version in formamide to be obtained. The calculated fully optimized equilibrium geometries of CHONH2 and H2O2 are in good agreement with experiment. However, during the rotation geo­ metry variations appear to be quite large. Application to formamide shows that torsion and in­ version are strongly coupled. The nature of the barriers calculated is analyzed in terms of the MINDO energy partitioning. Finally, it is shown that the frozen-frame variations of the charges on atoms and dipole moment of formamide, are strongly affected by the geometry optimization during rotation.

Investigation of the Molecular Geometry of Donor-Acceptor Complexes by the NDDO Method

1981 ◽  
Vol 36 (3) ◽  
pp. 283-285 ◽  
Author(s):  
Ärpad I. Kiss ◽  
Istvan Lukovits ◽  
Istvan Hargittai
Keyword(s):  
Experimental Evidence ◽  
Electron Donor ◽  
Electron Pair ◽  
Molecular Geometry ◽  
Energy Partitioning ◽  
Qualitative Model ◽  
Donor And Acceptor ◽  
Donor Acceptor ◽  
Opposing Effects ◽  
Semi Empirical

The molecular geometries of simple electron donor-acceptor complexes have been obtained from NDDO semi-empirical calculations. The results are in agreement with earlier observations based on experimental evidence concerning the characteristic geometrical variations in the donor and acceptor parts upon the complexation as compared with the free uncomplexed molecules. While the direction of the geometrical changes can be unambiguously predicted for the acceptor, these changes cannot be predicted for the donor as they are the results of opposing effects. It is generally observed that an increase in the bond angles is accompanied by bond shortening and vice versa. In order to interpret the results, calculated quantities from the energy partitioning have been attributed to electron pair repulsions and non-bonded atom-atom repulsions in a qualitative model

Semi-empirical evaluation of Sr-Ar difference potentials

1986 ◽  
Vol 47 (7) ◽  
pp. 1149-1154
Author(s):  
Le Quang Rang ◽  
D. Voslamber
Keyword(s):  
Empirical Evaluation ◽  
Difference Potentials ◽  
Semi Empirical
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