Including the Effect of Solvent on Quantum Mechanical Calculations: The Continuum Model Approach.
-
Upload
christiana-nicholson -
Category
Documents
-
view
221 -
download
3
Transcript of Including the Effect of Solvent on Quantum Mechanical Calculations: The Continuum Model Approach.
![Page 1: Including the Effect of Solvent on Quantum Mechanical Calculations: The Continuum Model Approach.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649d0d5503460f949e1a12/html5/thumbnails/1.jpg)
Including the Effect of Solvent on Quantum Mechanical
Calculations:
The Continuum Model Approach
![Page 2: Including the Effect of Solvent on Quantum Mechanical Calculations: The Continuum Model Approach.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649d0d5503460f949e1a12/html5/thumbnails/2.jpg)
SOLVENT MODELS
• Classical Ensemble Treatments
• Mixed QM/MM
• Quantum Mechanical Reaction Fields
![Page 3: Including the Effect of Solvent on Quantum Mechanical Calculations: The Continuum Model Approach.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649d0d5503460f949e1a12/html5/thumbnails/3.jpg)
SOLVENT MODELS
• Classical Ensemble Treatments
• Mixed QM/MM
• Quantum Mechanical Reaction Fields
truncated electrostatics
complete electrostatics
![Page 4: Including the Effect of Solvent on Quantum Mechanical Calculations: The Continuum Model Approach.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649d0d5503460f949e1a12/html5/thumbnails/4.jpg)
SOLVENT MODELS
• Classical Ensemble Treatments
• Mixed QM/MM
• Quantum Mechanical Reaction Fields
truncated electrostatics Onsager Sphere Method
complete electrostatics
![Page 5: Including the Effect of Solvent on Quantum Mechanical Calculations: The Continuum Model Approach.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649d0d5503460f949e1a12/html5/thumbnails/5.jpg)
SOLVENT MODELS
• Classical Ensemble Treatments
• Mixed QM/MM
• Quantum Mechanical Reaction Fields
truncated electrostatics Onsager Sphere Method Ellipsoidal Methods
complete electrostatics
![Page 6: Including the Effect of Solvent on Quantum Mechanical Calculations: The Continuum Model Approach.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649d0d5503460f949e1a12/html5/thumbnails/6.jpg)
SOLVENT MODELS
• Classical Ensemble Treatments
• Mixed QM/MM
• Quantum Mechanical Reaction Fields
truncated electrostatics Onsager Sphere Method Ellipsoidal Methods SAM1
complete electrostatics
![Page 7: Including the Effect of Solvent on Quantum Mechanical Calculations: The Continuum Model Approach.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649d0d5503460f949e1a12/html5/thumbnails/7.jpg)
SOLVENT MODELS
• Classical Ensemble Treatments
• Mixed QM/MM
• Quantum Mechanical Reaction Fields
truncated electrostatics Onsager Sphere Method Ellipsoidal Methods SAM1
complete electrostatics polarizable continuum model (PCM)
![Page 8: Including the Effect of Solvent on Quantum Mechanical Calculations: The Continuum Model Approach.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649d0d5503460f949e1a12/html5/thumbnails/8.jpg)
SOLVENT MODELS
• Classical Ensemble Treatments
• Mixed QM/MM
• Quantum Mechanical Reaction Fields
truncated electrostatics Onsager Sphere Method Ellipsoidal Methods SAM1
complete electrostatics polarizable continuum model (PCM) isodensity PCM
![Page 9: Including the Effect of Solvent on Quantum Mechanical Calculations: The Continuum Model Approach.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649d0d5503460f949e1a12/html5/thumbnails/9.jpg)
SOLVENT MODELS
• Classical Ensemble Treatments
• Mixed QM/MM
• Quantum Mechanical Reaction Fields
truncated electrostatics Onsager Sphere Method Ellipsoidal Methods SAM1
complete electrostatics polarizable continuum model (PCM) isodensity PCM conductor-like PCM
![Page 10: Including the Effect of Solvent on Quantum Mechanical Calculations: The Continuum Model Approach.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649d0d5503460f949e1a12/html5/thumbnails/10.jpg)
Onsager Self-ConsistentReaction Field (SCRF)
3
2( 1)
(1 2 )E D
a
����������������������������
Volume of sphere chosen based on molecular volume
![Page 11: Including the Effect of Solvent on Quantum Mechanical Calculations: The Continuum Model Approach.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649d0d5503460f949e1a12/html5/thumbnails/11.jpg)
Implementation of Onsager SCRF Method
Wong - Wiberg - Frisch 1991-1992
Analytical First and Second Derivatives
Molecular Geometries Vibrational Frequencies
Fast, but Limited
Molecules that are not spheres? Other solvent-solute interaction?
![Page 12: Including the Effect of Solvent on Quantum Mechanical Calculations: The Continuum Model Approach.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649d0d5503460f949e1a12/html5/thumbnails/12.jpg)
Furfuraldehyde conformational equilibrium
Which isomer is more stable? How much more stable?
![Page 13: Including the Effect of Solvent on Quantum Mechanical Calculations: The Continuum Model Approach.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649d0d5503460f949e1a12/html5/thumbnails/13.jpg)
Furfuraldehyde conformational equilibrium
Which isomer is more stable? How much more stable?
Syn - Anti [kcal/mol] Onsager* Expt.Gas phase +0.93 +0.82dimethyl ether (-120) -0.13 -0.58
*Theoretical model is RHF/6-31+G(d)//RHF/6-31G(d) gas phase geometry
![Page 14: Including the Effect of Solvent on Quantum Mechanical Calculations: The Continuum Model Approach.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649d0d5503460f949e1a12/html5/thumbnails/14.jpg)
Furfuraldehyde conformational equilibrium
Which isomer is more stable? How much more stable?
Syn - Anti [kcal/mol] Onsager* Expt.Gas phase +0.93 +0.82dimethyl ether (-120) +0.22 -0.58
*Theoretical model is B3LYP/6-31+G(d)//RHF/6-31G(d) gas phase geometry
![Page 15: Including the Effect of Solvent on Quantum Mechanical Calculations: The Continuum Model Approach.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649d0d5503460f949e1a12/html5/thumbnails/15.jpg)
(2 1)( 1)( 1)
[ ( 1)]E a D
����������������������������
Dipole formula can be generalized forhigher-order electrostatic terms:
![Page 16: Including the Effect of Solvent on Quantum Mechanical Calculations: The Continuum Model Approach.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649d0d5503460f949e1a12/html5/thumbnails/16.jpg)
Furfuraldehyde conformational equilibrium
Syn - Anti [kcal/mol] Spherical CavityDipole -0.13Quadrupole -0.75Octapole +0.29Hexadecapole +0.42Expt -0.58
Solvent is dimethylether
![Page 17: Including the Effect of Solvent on Quantum Mechanical Calculations: The Continuum Model Approach.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649d0d5503460f949e1a12/html5/thumbnails/17.jpg)
Rivail and Rinaldi (QCPE 1992)
Extended to ellipsoidal cavity shape
• used VDW radii to determine• sixth-order electrostatics• first derivatives
![Page 18: Including the Effect of Solvent on Quantum Mechanical Calculations: The Continuum Model Approach.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649d0d5503460f949e1a12/html5/thumbnails/18.jpg)
Rivail and Rinaldi (QCPE 1992)
Extended to ellipsoidal cavity shape
• used VDW radii to determine• sixth-order electrostatics• first derivatives
2-nitrovinylamine rotational barrier:
E Form Z form
![Page 19: Including the Effect of Solvent on Quantum Mechanical Calculations: The Continuum Model Approach.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649d0d5503460f949e1a12/html5/thumbnails/19.jpg)
Rivail and Rinaldi (QCPE 1992)
E Form Z form
TS
![Page 20: Including the Effect of Solvent on Quantum Mechanical Calculations: The Continuum Model Approach.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649d0d5503460f949e1a12/html5/thumbnails/20.jpg)
Rivail and Rinaldi (QCPE 1992)
HF/6-31+G(D) TS-Z [kcal/mol] Gas Phase Calculated 47.3 L=1 Ellipse 32.2 L=2 Ellipse 29.3 L=3 Ellipse 24.5 L=4 Ellipse 23.6 L=5 Ellipse 23.6 L=6 Ellipse 23.0 L=6 Ellipse Geom Opt 21.9 Expt 21.3
2-nitrovinylamine rotational barrier:
Solvent is N,N-dimethylformamide
![Page 21: Including the Effect of Solvent on Quantum Mechanical Calculations: The Continuum Model Approach.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649d0d5503460f949e1a12/html5/thumbnails/21.jpg)
What if our molecule is not in theshape of a basketball or football?
![Page 22: Including the Effect of Solvent on Quantum Mechanical Calculations: The Continuum Model Approach.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649d0d5503460f949e1a12/html5/thumbnails/22.jpg)
Isodensity Polarizable Continuum Model
Keith - Foresman - Wiberg - Frisch (JPC 1996)
Cavity surface defined as an isodensity of the solute 0.0004 is used because it gives expt molecular volumes
Solute is polarized by the solvent represented by point charges on cavity surface
Self-Consistent Solution is found: cavity changes each macroiteration
![Page 23: Including the Effect of Solvent on Quantum Mechanical Calculations: The Continuum Model Approach.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649d0d5503460f949e1a12/html5/thumbnails/23.jpg)
Furfuraldehyde conformational equilibrium
Model is B3LYP/6-31+G(d)//HF/6-31G(d) gas
![Page 24: Including the Effect of Solvent on Quantum Mechanical Calculations: The Continuum Model Approach.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649d0d5503460f949e1a12/html5/thumbnails/24.jpg)
Acetone hydration energy
3.8 kcal/molEXPThydrG
![Page 25: Including the Effect of Solvent on Quantum Mechanical Calculations: The Continuum Model Approach.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649d0d5503460f949e1a12/html5/thumbnails/25.jpg)
Really two problems here:
1. Experiment is Free Energy, calculationincludes only solute-solvent electrostaticinteraction.
2. Hydrogen Bonding
![Page 26: Including the Effect of Solvent on Quantum Mechanical Calculations: The Continuum Model Approach.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649d0d5503460f949e1a12/html5/thumbnails/26.jpg)
Pisa Polarizable Continuum Model (PCM)
Miertus - Tomasi - Mennucci - Cammi (1980-present)
Cavity based on overlapping spheres centered on atoms
Free Energy Terms built in as solvent parameters cavitation energy dispersion energy repulsion energy
Specialized Surface Charge Schemes patches for interface regions
![Page 27: Including the Effect of Solvent on Quantum Mechanical Calculations: The Continuum Model Approach.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649d0d5503460f949e1a12/html5/thumbnails/27.jpg)
Conductor Polarizable Continuum Model (CPCM)
Barone - Cossi ( JPCA 1998)
Extension of Pisa Model
More Appropriate for Polar Liquids electrostatic potential goes to zero on the surface
Specialized Surface Charge Schemes patches for interface regions
![Page 28: Including the Effect of Solvent on Quantum Mechanical Calculations: The Continuum Model Approach.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649d0d5503460f949e1a12/html5/thumbnails/28.jpg)
Conductor Polarizable Continuum Model (CPCM)
Barone - Cossi ( JPCA 1998)
Free Energies of Hydration:
CPCM Model; basis set is 6-31G(d); TSNum=60; gas phase geometries; Barone & Cossi, JPCA 1998.
![Page 29: Including the Effect of Solvent on Quantum Mechanical Calculations: The Continuum Model Approach.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649d0d5503460f949e1a12/html5/thumbnails/29.jpg)
Conductor Polarizable Continuum Model (CPCM)
Barone - Cossi ( JPCA 1998)
Free Energies of Hydration:
CPCM Model; basis set is 6-31G(d); TSNum=60; gas phase geometries; Barone & Cossi, JPCA 1998.
Problem:Cavitytied toMethod
NotObviousHow todetermineradii ofspheres
![Page 30: Including the Effect of Solvent on Quantum Mechanical Calculations: The Continuum Model Approach.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649d0d5503460f949e1a12/html5/thumbnails/30.jpg)
Isodensity Methods better for determining cavitywithout parameterization
Pisa model parameters useful when non-electrostaticterms are important
SUMMARY
In Progress:
Merging the two methods
![Page 31: Including the Effect of Solvent on Quantum Mechanical Calculations: The Continuum Model Approach.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649d0d5503460f949e1a12/html5/thumbnails/31.jpg)
Other Applications
![Page 32: Including the Effect of Solvent on Quantum Mechanical Calculations: The Continuum Model Approach.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649d0d5503460f949e1a12/html5/thumbnails/32.jpg)
Menschutkin Reaction:
![Page 33: Including the Effect of Solvent on Quantum Mechanical Calculations: The Continuum Model Approach.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649d0d5503460f949e1a12/html5/thumbnails/33.jpg)
Menschutkin Reaction:
Is this reaction endothermic or exothermic?
![Page 34: Including the Effect of Solvent on Quantum Mechanical Calculations: The Continuum Model Approach.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649d0d5503460f949e1a12/html5/thumbnails/34.jpg)
Menschutkin Reaction:
Is this reaction endothermic or exothermic?
What is the activation energy and mechanism?
![Page 35: Including the Effect of Solvent on Quantum Mechanical Calculations: The Continuum Model Approach.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649d0d5503460f949e1a12/html5/thumbnails/35.jpg)
Menschutkin Reaction:
Is this reaction endothermic or exothermic?
What is the activation energy and mechanism?
How does solvent influence this?
![Page 36: Including the Effect of Solvent on Quantum Mechanical Calculations: The Continuum Model Approach.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649d0d5503460f949e1a12/html5/thumbnails/36.jpg)
Menschutkin Reaction:
G Ea gas 120.0 Onsager 10.0 24.2 PCM -21.5 24.8 Expt* -30.0 24.0 Energies in kcal/mol *CH3I in water
![Page 37: Including the Effect of Solvent on Quantum Mechanical Calculations: The Continuum Model Approach.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649d0d5503460f949e1a12/html5/thumbnails/37.jpg)
![Page 38: Including the Effect of Solvent on Quantum Mechanical Calculations: The Continuum Model Approach.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649d0d5503460f949e1a12/html5/thumbnails/38.jpg)
Solvent Effects on Electronic Spectra
![Page 39: Including the Effect of Solvent on Quantum Mechanical Calculations: The Continuum Model Approach.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649d0d5503460f949e1a12/html5/thumbnails/39.jpg)
Absorption Spectrum of Acetone
![Page 40: Including the Effect of Solvent on Quantum Mechanical Calculations: The Continuum Model Approach.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649d0d5503460f949e1a12/html5/thumbnails/40.jpg)
Acetone Acetone – 2 water complex
Gas phase 4.42 eV 4.59 eV CPCM 4.57 eV 4.70 eV
Experimental: 4.43 (cyclohexane) 4.67 (water)
![Page 41: Including the Effect of Solvent on Quantum Mechanical Calculations: The Continuum Model Approach.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649d0d5503460f949e1a12/html5/thumbnails/41.jpg)
L E P r i m a r y L o c a l E x c i t e d S t a t e
S h o r t e r W a v e l e n g t h ( B B a n d )
C T S e c o n d a r y C h a r g e T r a n s f e r S t a t e
L o n g e r W a v e l e n g t h ( A B a n d )
700 nm300 nm
B
A
DUAL FLUORESCENCE
![Page 42: Including the Effect of Solvent on Quantum Mechanical Calculations: The Continuum Model Approach.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649d0d5503460f949e1a12/html5/thumbnails/42.jpg)
4-aminobenzonitrile4ABN
4-dimethylaminobenzonitrile4DMABN
![Page 43: Including the Effect of Solvent on Quantum Mechanical Calculations: The Continuum Model Approach.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649d0d5503460f949e1a12/html5/thumbnails/43.jpg)
Twisted Intermolecular Charge TransferTICT
![Page 44: Including the Effect of Solvent on Quantum Mechanical Calculations: The Continuum Model Approach.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649d0d5503460f949e1a12/html5/thumbnails/44.jpg)
![Page 45: Including the Effect of Solvent on Quantum Mechanical Calculations: The Continuum Model Approach.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649d0d5503460f949e1a12/html5/thumbnails/45.jpg)
![Page 46: Including the Effect of Solvent on Quantum Mechanical Calculations: The Continuum Model Approach.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649d0d5503460f949e1a12/html5/thumbnails/46.jpg)
![Page 47: Including the Effect of Solvent on Quantum Mechanical Calculations: The Continuum Model Approach.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649d0d5503460f949e1a12/html5/thumbnails/47.jpg)
![Page 48: Including the Effect of Solvent on Quantum Mechanical Calculations: The Continuum Model Approach.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649d0d5503460f949e1a12/html5/thumbnails/48.jpg)
Thanks
• AEleen Frisch• Ken Wiberg, Yale University• Mike Frisch, Gaussian Inc.• Todd Keith, SemiChem• Hans Peter Luthi, ETH Zurich• Brian Williams, Bucknell Univeristy