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The VB calculations are the same as the calculations performed above. Try to understand the BFI section, perform the calculations and compare the differences of barrier heights, resonance energies and performances with and without $BFI.
 
The VB calculations are the same as the calculations performed above. Try to understand the BFI section, perform the calculations and compare the differences of barrier heights, resonance energies and performances with and without $BFI.
  
 +
{| class="collapsible collapsed wikitable"
 +
|-
 +
!'''Answer'''
 +
|-
 +
|
 +
=====Weights of Structures=====
 +
<center>
 +
{| border="1"
 +
|+ Weights of structures at Reactant Geometry
 +
! scope="col" |
 +
! scope="col" | S1
 +
! scope="col" | S2
 +
! scope="col" | S3
 +
! scope="col" | S4
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! scope="col" | S5
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! scope="col" | S6
 +
|-
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! scope="row"      |VBSCF
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| 0.632 || 0.003 || 0.001 || 0.299 || 0.064 || 0.000
 +
|-
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! scope="row"    | BOVB
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| 0.566 || 0.061 || 0.005 || 0.288 || 0.081 || 0.000
 +
|-
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! scope="row"      | VBSCF/PCM
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| 0.645 || 0.002 || 0.001 || 0.279 || 0.073 || 0.000
 +
|-
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! scope="row"      | BOVB/PCM
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| 0.599 || -0.019 || -0.007 || 0.337 || 0.089 || 0.000
 
|}
 
|}
 +
</center>
 +
<br>
 +
<center>
 +
{| border="1"
 +
|+ Weights of structures at Transition State Geometry
 +
! scope="col" |
 +
! scope="col" | S1
 +
! scope="col" | S2
 +
! scope="col" | S3
 +
! scope="col" | S4
 +
! scope="col" | S5
 +
! scope="col" | S6
 +
|-
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! scope="row"      |VBSCF
 +
| 0.239 || 0.240 || 0.027 || 0.496 || -0.001 || -0.001
 +
|-
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! scope="row"    | BOVB
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| 0.263 || 0.263 || 0.043 || 0.416 || 0.007 || 0.007
 +
|-
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! scope="row"      | VBSCF/PCM
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| 0.220 || 0.220 || 0.020 || 0.542 || -0.001 || -0.001
 +
|-
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! scope="row"      | BOVB/PCM
 +
| 0.251 || 0.251 || 0.036 || 0.452 || 0.005 || 0.005
 +
|}
 +
</center>
 +
 +
=====Barrier of the Reaction=====
 +
<center>
 +
{| border="1"
 +
|+ Energies (a.u.) and Barriers (kcal/mol) of <math>\textrm{S}_{\textrm{N}}2</math> Reaction
 +
! scope="col" |
 +
! scope="col" | VBSCF
 +
! scope="col" | BOVB
 +
! scope="col" | VBSCF/PCM
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! scope="col" | BOVB/PCM
 +
|-
 +
! scope="row"      |Reactant
 +
| -958.65818 || -958.67599 || -958.75774 || -958.78203
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|-
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! scope="row"    | Trasition State
 +
| -958.62157 || -958.65321 || -958.71004 || -958.73960
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|-
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! scope="row"      | Barrier
 +
| 23.0 || 14.3 || 29.9 || 26.6
 +
|}
 +
</center>
 +
 +
=====Resonance Energ of Transition State=====
 +
<center>
 +
{| border="1"
 +
|+ Energies (a.u.) and Resonance Energies (kcal/mol) of Transition State
 +
! scope="col" |
 +
! scope="col" | VBSCF
 +
! scope="col" | BOVB
 +
! scope="col" | VBSCF/PCM
 +
! scope="col" | BOVB/PCM
 +
|-
 +
! scope="row"    | All Structures
 +
| -958.62157 || -958.65321 || -958.71004 || -958.73960
 +
|-
 +
! scope="row" | Reactant
 +
| -958.59188 || -958.60816 || -958.68547 || -958.70142
 +
|-
 +
! scope="row" | Product
 +
| -958.59188 || -958.60816 || -958.68547 || -958.70142
 +
|-
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! scope="row"      | Resonance Energy
 +
| 18.6 || 28.3 || 15.4 || 23.9
 +
|}
 +
</center>
  
[[Answer Exercise1 of tutorial 3|>> Answer]]
+
=====Resonance Energ of Transition State=====
 +
<center>
 +
{| border="1"
 +
|+ Energies(a.u.) and Resonance Energies (kcal/mol) of Reactant
 +
! scope="col" |
 +
! scope="col" | VBSCF
 +
! scope="col" | BOVB
 +
! scope="col" | VBSCF/PCM
 +
! scope="col" | BOVB/PCM
 +
|-
 +
! scope="row"    | All Structures
 +
| -958.65818 || -958.67599 || -958.75774 || -958.78203
 +
|-
 +
! scope="row" | Reactant
 +
| -958.56752 || -958.67272 || -958.75734 || -958.77250 
 +
|-
 +
! scope="row" | Product
 +
| -958.31845 || -958.31845 || -958.57917 || -958.58246
 +
|-
 +
! scope="row"      | Resonance Energy
 +
| 0.4 || 2.1 || 0.3 || 6.0
 +
|}
 +
</center>
 +
|}
 +
|}
  
  

Version du 12 juillet 2012 à 11:43

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Valence Bond State correlation diagrams

Exercise 1 : Computation of state correlation Diagrams for a 3 centers / 4 electrons system

In this exercise the <math>\textrm{S}_{\textrm{N}}2</math> reaction Cl<math>{}^{-}</math> + CH3Cl -> ClCH3 + Cl<math>{}^{-}</math> will be studied in both vacuum and solution. Valence Bond State Correlation Diagrams (VBSCD) will be constructed at <math>\pi</math>-D-BOVB level. There are two parts in this exercise: basic part and optional part. The basic part is performed with MCP-DZP basis set in which the inner orbitals in Cl and C are described with MCP pseudo potential. The optional part is performed with 6-31+G* basis set, using the general specification for the xmvb input (expert users). Only reactant and transition state will be computed in this exercise, which is sufficient to build the VBSCD diagrams.


>> general guidelines for BOVB calculations