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What Theory Can Do

What Theory Can Do. Strength and Weakness. 理论计算起到了非常重要的作用. Fig. 1 The linkages between thermochemical kinetics and other subjects. Ref. Walsh, R. Chem. Soc. Rev. 2008, 37 , 686. 2014/6/6. What Theory Can Do. 2. For small and regular molecules Chemical Accuracy:

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What Theory Can Do

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  1. What Theory Can Do Strength and Weakness

  2. 理论计算起到了非常重要的作用 Fig. 1 The linkages between thermochemical kinetics and other subjects. Ref. Walsh, R. Chem. Soc. Rev. 2008, 37, 686. 2014/6/6 What Theory Can Do 2

  3. For small and regular molecules Chemical Accuracy: Energetics: Error < 1 kcal/mol Structures: Error in Bond Lengths < 0.01 Å Frequencies: A few cm-1 Strength What Theory Can Do

  4. Ref: Hoffman, B.C.; Sherrill, C. D.; Schaefer III, H. F. J. Chem. Phys.1997, 107(24), 10616. What Theory Can Do

  5. Ref: Bak K. L. et al. J. Chem. Phys.2001, 114(15), 6548. 2014/6/6 What Theory Can Do 5

  6. Ref:Bak K. L. et al. J. Chem. Phys.2001, 114(15), 6548. 2014/6/6 What Theory Can Do 6

  7. Ref:Bak K. L. et al. J. Chem. Phys.2001, 114(15), 6548. 2014/6/6 What Theory Can Do 7

  8. Ref: Bak K. L. et al. J. Chem. Phys.2001, 114(15), 6548. 2014/6/6 What Theory Can Do 8

  9. Ref: Abrams, M. L. PhD Thesis, General-Order Single-Reference and Multi-Reference Methods in Quantum Chemistry, 2005 2014/6/6 What Theory Can Do 9

  10. Ref: Abrams, M. L. PhD Thesis, General-Order Single-Reference and Multi-Reference Methods in Quantum Chemistry, 2005 • BH, CH+, NH, OH+, HF, C2 2014/6/6 What Theory Can Do 10

  11. Accurate Calculations Can Give Better Results Than Experiment Table VII. Enthalpies of formation at 298 K (in kcal mol–1). Ref: Haworth, N. L.; Bacskay, G. B. J. Chem. Phys.2002, 117(24), 11175. 2014/6/6 What Theory Can Do 11

  12. Accurate Calculations Can Give Better Results Than Experiment Table VII. Average Error in Atomization Energy at 0 K (in kcal mol–1). (H2O,C2H2,CH3,CH4,CH,CO2,CO,F2,HF,N2,NH3,N2O,NO,O2,O3,NO2,Cl2,ClF,CS,H2S,HCl,HOCl,PH3,SO,SO2,OCS,ClCN,C2H4,H2CO,HNO) Ref: Karton, A.; Rabinovich, E.; Martin J. M. L.; Ruscic, Branko, R. J. Chem. Phys.2006, 125, 144108. 2014/6/6 What Theory Can Do 12

  13. Accurate Calculations Can Give Better Results Than Experiment Table I. Recommended Gas-Phase Heats of Formation at 0 K (in kcal mol–1). Ref: Karton, A.; Martin J. M. L. J. Phys.Chem. A 2007, 111(26), 5936. 2014/6/6 What Theory Can Do 13

  14. Accurate Calculations Can Give Better Results Than Experiment Table 8 Ionization energy and heat of formation of B2F4 at 298 K. Ref: Li, Z. H.; Fan, K. N. J. Phys.Chem. A 2002, 106(28), 6659. 2014/6/6 What Theory Can Do 14

  15. Weakness Results sensitive to Basis set, Method Very Expensive For Reliable Predictions Wrong conclusion from inaccurate calculations DFT: Good in geometry, frequency, long way to reliable quantitative predictions 2014/6/6 What Theory Can Do 15

  16. Everyone uses “Density Functional Theory” Publications from 1980 to 2011 in SCI-Expanded

  17. Everyone uses B3LYP Publications from 1994 to 2010 in SCI-Expanded

  18. DFT: Good in Geometry MUE in Bond Length (Å)Ref: Zhao, Y.; Truhlar, D. G. Theo. Chem. Acc. 2008, 120, 215.

  19. DFT: Not So Bad in Frequency and ZPE Error in Frequency (cm-1) and ZPE (kcal/mol)Ref: Zhao, Y.; Truhlar, D. G. Theo. Chem. Acc. 2008, 120, 215.

  20. Bad Thing

  21. Small Vibrational Frequency Very Sensitive to Basis Set Table 1 The lowest harmonic vibrational frequency (cm-1) of the eclipsed (D2h) and staggered (D2d) conformations of B2F4. Ref: Li, Z. H.; Fan, K. N. J. Phys.Chem. A 2002, 106(28), 6659. 2014/6/6 What Theory Can Do 21

  22. The low harmonic vibrational frequencies (cm-1) of Zn(C2H4)42+ by the B3PW91 method. Li, Z. H., unpublished Frequency Calculation: Sensitive to Grid Point 2014/6/6 What Theory Can Do 22

  23. Very Slow Basis-Set ConvergenceRef: Persson, B. J.; Taylor, P. R.; Lee, T. J. J. Chem. Phys. 1997, 107(13), 5051 2014/6/6 What Theory Can Do 23

  24. Wrong Conclusion Can be Drawn from Cheap CalculationRef: Persson, B. J.; Taylor, P. R.; Lee, T. J. J. Chem. Phys. 1997, 107(13), 5051 2014/6/6 What Theory Can Do 24

  25. Wrong Conclusion Can be Drawn from Cheap CalculationRef: Persson, B. J.; Taylor, P. R.; Lee, T. J. J. Chem. Phys. 1997, 107(13), 5051 2014/6/6 What Theory Can Do 25

  26. Conclusion by Taylor P. R. in 2000 • So, we’ve exhausted our armoury and we disagree with experiment by 0.03 Å on the bond length and by up to 25 cm−1 (!) in the vibrational fundamentals. • In addition, the heat of the reaction P4 → 2P2 is estimated computationally to be 63.2 kcal/mol, whereas the experimental estimate is around 54 kcal/mol. • NIST thermochemist: “All phosphorus thermochemical results are suspect.”

  27. New Conclusion by Martin JML in 2007Ref. Karton, A.; Martin, J. M. L. Mol. Phys.2007, 105(19-22), 2499. • Contrary to previous studies, we find the experimental thermochemistry to be fundamentally sound. The reaction enthalpy for P4 -> 2P2 has a very significant contribution from post-CCSD(T) correlation effects. We derive a gas-phase heat of formation for the phosphorus atom of H0(f) [P(g)] = 75.54  0.1 kcal mol-1 and H298(f) [P(g)] = 75.74  0.1 kcal mol-1, in the upper half of the CODATA uncertainty interval. • CODATA: H0(f) [P(g)] = 75.45  0.24

  28. Difficult Cases: Open-Shell Systems with Strong Multireference Character Potential Energy Surface of HF (kcal/mol), basis set: DZP Siesta 1.3f (UPBE, RPBE); 6-311++G(2df,2p) for Others

  29. Difficult Cases: Open-Shell Systems with Strong Multireference Character Error in Potential Energy Surface of HF (kcal/mol), basis set: DZP Siesta 1.3f (UPBE, RPBE); 6-311++G(2df,2p) for Others

  30. Potential Energy Surface of N2Ref: Chan, G.K.; Kállay, M.; Gauss, J. J. Chem. Phys.2004, 121(13), 6110. N2 Energy Curve 2014/6/6 What Theory Can Do 30

  31. Difficult Cases: Open-Shell Systems with Strong Multireference Character Relative Energy of FeO2−(in kcal/mol)Ref: Li, Z. H.; Gong, Y.; Fan, K. N.; Zhou, M. F. J. Phys. Chem. A.2008, 112(51), 13641-13649

  32. Difficult Cases: Open-Shell Systems with Strong Multireference Character 3 Vibrational Frequency of Relative Energy of FeO2-Ref: Li, Z. H.; Gong, Y.; Fan, K. N.; Zhou, M. F. J. Phys. Chem. A.2008, in press

  33. Difficult Cases: Open-Shell Systems with Strong Multireference Character Excitation Energy of Fe2− (Relative to 8g−Ground State)Ref: Sorkin, A.; Iron, M. A.; Truhlar, D. G. J. Chem. Theo. Comput. 2008, 4(2), 307.

  34. Difficult Cases: Open-Shell Systems with Strong Multireference Character Excitation Energy of FeO+ (Relative to 4+Ground State)Ref: Sorkin, A.; Iron, M. A.; Truhlar, D. G. J. Chem. Theo. Comput. 2008, 4(2), 307.

  35. Difficult Cases: Open-Shell Systems with Strong Multireference Character Bond Length of Cr2Ref: Schultz N. E.; Zhao, Y.; Truhlar, D. G. J. Phys. Chem. A 2005, 109, 4388.

  36. Difficult Cases: Open-Shell Systems with Strong Multireference Character Error in the Bond Energies (kcal/mol) of Ag2, AgCu, Cr2, Cu2, Mo2, Ni2, V2, Zr2, ZrVRef: Schultz N. E.; Zhao, Y.; Truhlar, D. G. J. Phys. Chem. A 2005, 109, 4388.

  37. Difficult Cases: Open-Shell Systems with Strong Multireference Character Computed J12 (cm−1) values for [Cu2Cl6]2− on passing from square planar (=0°) to pseudo-tetrahedral geometriesRef: Bencini, A. Inorg. Chimica. Acta 2008, 361, 3820.

  38. Difficult Cases (DFT): Noncovalent Interactions Ref: Zhao, Y.; Truhlar, D. G. Acc. Chem. Res. 2008, 41(2), 157.

  39. Difficult Cases (DFT): Noncovalent Interactions Ref: Zhao, Y.; Truhlar, D. G. Acc. Chem. Res. 2008, 41(2), 157.

  40. Difficult Cases (DFT): Noncovalent Interactions Ref: Zhao, Y.; Truhlar, D. G. Acc. Chem. Res. 2008, 41(2), 157.

  41. Difficult Cases: Charge Transfer Excitation Energies Excitation Energies (eV)Ref: Zhao, Y.; Truhlar, D. G. Theo. Chem. Acc. 2008, 120, 215.

  42. Donald G. Truhlar

  43. DFT: Reaction Energy and Equilibrium Constants Error in Reaction Energy at 0 K (kcal/mol) Li Z. H. unpublished.

  44. DFT: Reaction Energy and Equilibrium Constants Equilibrium Constant at 298 K (KDFT/KAcc) Li Z. H. unpublished.

  45. Reaction Energy at 0 K (kcal/mol) Free energy change (kcal/mol) at 800 K

  46. DFT: Bad Energy Barriers for Hydrogen Transfer Reactions Ref: Zhao, Y.; Lynch, B. J.; Truhlar, D. G. J. Phys. Chem. A2004, 108, 2715.

  47. Prediction on Selectivity? Figure From: Somorjai, G. A.; Park, J. Y. Angew. Chem. Int. Ed. 2008, 47, 9212. 不同的选择性对应的自由能垒的差别 (kcal/mol)

  48. 怎样做好的计算 • Right Reason for the Right Answer

  49. 怎样做好的计算 • 了解所研究的体系 • 建立合理的模型 • 选择合适的方法 • 理论方法：HF, MP2, DFT, 半经验，经验 • 基组 • 可靠性 • 性价比 • 分析结果 • 得到结论 • Right Reason for the Right Answer

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