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Ligne 63 : Ligne 63 :
 
   BLW-ED Analysis
 
   BLW-ED Analysis
 
   C1   
 
   C1   
 +
C    6.0  0.000000  -1.086858    2.236154
 +
C    6.0  0.000000    0.000000    1.489418
 
  C    6.0  0.000000    0.000000    0.000000
 
  C    6.0  0.000000    0.000000    0.000000
  C    6.0   0.000000   0.000000   1.489418
+
  C    6.0 -1.086858   0.000000   -0.746736
 
  H    1.0  0.967527    0.000000  -0.478451
 
  H    1.0  0.967527    0.000000  -0.478451
 
  H    1.0  0.000000    0.967527    1.967869
 
  H    1.0  0.000000    0.967527    1.967869
C    6.0  -1.086858    0.000000  -0.746736
 
C    6.0  0.000000  -1.086858    2.236154
 
 
  H    1.0  -2.072275    0.000000  -0.314213
 
  H    1.0  -2.072275    0.000000  -0.314213
 
  H    1.0  -1.029400    0.000000  -1.820913
 
  H    1.0  -1.029400    0.000000  -1.820913
 
  H    1.0  0.000000  -2.072275    1.803631
 
  H    1.0  0.000000  -2.072275    1.803631
 
  H    1.0  0.000000  -1.029400    3.310331
 
  H    1.0  0.000000  -1.029400    3.310331
$END
+
$END
 +
 
 
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Version du 11 juillet 2012 à 16:48

return to Tutorial n°4 Two geometries are provided the planar and the twisted where a vinyl part C1 C5 has been twisted by 90°. this second moieties has its pi orbitals along the y direction.

Evaluation of the conjugaison

Localization of px-like pi orbitals to deconjugate keeping planar

Evaluation of the hyperconjugaison in the twisted form

In the BLW part we localize px-like pi orbitals of atoms C2 and C6 and py-like orbitals for C1 C5 to avoid hyperconjugaison.

We find
delocalized planar -155.8824504889
localized planar -155.8603462862 (13.9 kcal/mol)
Twisted -155.8695790387 ( 8.1 kcal/mol)
Twisted but local -155.8537320442 (18.0 kcal/mol)

Hence conjugaison is 13.9 kcal/mol, and the hyper conjugaison in the twisted form is as large as 9.9 kcal/mol