1. Including the Effect of Solvent on Quantum Mechanical Calculations: The Continuum Model Approach

2. SOLVENT MODELS Classical Ensemble Treatments Mixed QM/MM Quantum Mechanical Reaction Fields

3. SOLVENT MODELS Classical Ensemble Treatments Mixed QM/MM Quantum Mechanical Reaction Fields  truncated electrostatics  complete electrostatics

4. SOLVENT MODELS Classical Ensemble Treatments Mixed QM/MM Quantum Mechanical Reaction Fields  truncated electrostatics Onsager Sphere Method  complete electrostatics

5. SOLVENT MODELS Classical Ensemble Treatments Mixed QM/MM Quantum Mechanical Reaction Fields  truncated electrostatics Onsager Sphere Method Ellipsoidal Methods  complete electrostatics

6. SOLVENT MODELS Classical Ensemble Treatments Mixed QM/MM Quantum Mechanical Reaction Fields  truncated electrostatics Onsager Sphere Method Ellipsoidal Methods SAM1  complete electrostatics

7. 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)

8. 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

9. 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

10. Onsager Self-Consistent Reaction Field (SCRF) Volume of sphere chosen based on molecular volume

11. 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?

12. Furfuraldehyde conformational equilibrium Which isomer is more stable? How much more stable?

13. Furfuraldehyde conformational equilibrium Which isomer is more stable? How much more stable? Syn - Anti [kcal/mol] Onsager* Expt. Gas phase +0.93 +0.82 dimethyl ether (-120) -0.13 -0.58 *Theoretical model is RHF/6-31+G(d)//RHF/6-31G(d) gas phase geometry

14. Furfuraldehyde conformational equilibrium Which isomer is more stable? How much more stable? Syn - Anti [kcal/mol] Onsager* Expt. Gas phase +0.93 +0.82 dimethyl ether (-120) +0.22 -0.58 *Theoretical model is B3LYP/6-31+G(d)//RHF/6-31G(d) gas phase geometry

15. Dipole formula can be generalized for higher-order electrostatic terms:

16. Furfuraldehyde conformational equilibrium Syn - Anti [kcal/mol] Spherical Cavity Dipole -0.13 Quadrupole -0.75 Octapole +0.29 Hexadecapole +0.42 Expt -0.58 Solvent is dimethylether

17. Rivail and Rinaldi (QCPE 1992) Extended to ellipsoidal cavity shape used VDW radii to determine sixth-order electrostatics first derivatives

18. 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 FormZ form

19. Rivail and Rinaldi (QCPE 1992) E FormZ form TS

20. Rivail and Rinaldi (QCPE 1992) 2-nitrovinylamine rotational barrier: Solvent is N,N-dimethylformamide

21. What if our molecule is not in the shape of a basketball or football?

22. 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

23. Furfuraldehyde conformational equilibrium Model is B3LYP/6-31+G(d)//HF/6-31G(d) gas

24. Acetone hydration energy

25. Really two problems here: 1. Experiment is Free Energy, calculation includes only solute-solvent electrostatic interaction. 2. Hydrogen Bonding

26. 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

27. 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

28. 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.

29. 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: Cavity tied to Method Not Obvious How to determine radii of spheres

30. Isodensity Methods better for determining cavity without parameterization Pisa model parameters useful when non-electrostatic terms are important SUMMARY In Progress: Merging the two methods

31. Other Applications

32. Menschutkin Reaction:

33. Is this reaction endothermic or exothermic?

34. Menschutkin Reaction: Is this reaction endothermic or exothermic? What is the activation energy and mechanism?

35. Menschutkin Reaction: Is this reaction endothermic or exothermic? What is the activation energy and mechanism? How does solvent influence this?

36. Menschutkin Reaction:

38. Solvent Effects on Electronic Spectra

39. Absorption Spectrum of Acetone

41. DUAL FLUORESCENCE

42. 4-aminobenzonitrile 4ABN 4-dimethylaminobenzonitrile 4DMABN

43. Twisted Intermolecular Charge Transfer TICT

48. Thanks AEleen Frisch Ken Wiberg, Yale University Mike Frisch, Gaussian Inc. Todd Keith, SemiChem Hans Peter Luthi, ETH Zurich Brian Williams, Bucknell Univeristy