Performance of DFT

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Performance of DFT Sergio Aragon San Francisco State University CalTech PASI January 4-16, 2004 : 

Performance of DFT Sergio Aragon San Francisco State University CalTech PASI January 4-16, 2004

H2 Dissociation Curve: 

H2 Dissociation Curve

Performance: Ozone: 

Performance: Ozone

Slide4: 

Koch & Holthausen Bond lengths & Bond Angles

Octahedral Cr Complex: 

Octahedral Cr Complex

Octahedral Metallic Carbonyls: 

Octahedral Metallic Carbonyls

Vibrational Frequencies: 

Vibrational Frequencies

Thermochemistry: 

Thermochemistry

Ionization Energies: 

Ionization Energies HF under-estimates ionization energies: more correlation in the neutral than in the ion.

Electron Affinities: 

Electron Affinities Affinities are very problematic for HF//anything methods. Extra electron adds correlation and is very diffuse. DFT does reasonably well.

Excitation Energies: Ethylene: 

Excitation Energies: Ethylene Poor asymptotic behavior of ordinary functionals yields a deteriorating picture as the excitation energy increases. Asymptotically corrected functionals such as PBE perform as well as the very expensive CAS methods.

Dipole Moments: 

Dipole Moments HF predicts the wrong sign of the dipole moment for CO! DFT performs very well.

Polarizabilities: 

Polarizabilities Polarizabilities are inversely proportional to orbital energy differences. DFT, with poor asymptotics, has high values of the HOMO energy and overestimates the polarizability.

Hydrogen bonding: Water Dimer: 

Hydrogen bonding: Water Dimer The fabulous numbers for the BLYP functional have been shown to be due to fortuitous error cancellation. Hybrid functionals do not overperform the HF//MP2 level.

Further Study: 

Further Study Koch, W. and Holthausen, M.C., “A Chemist’s Guide to Density Functional Theory”, Wiley-VCH: New York, 2000. Further comparisons are available on: IR intensities NMR chemical shifts and spin-spin couplings Hyperpolarizabilities ESR tensors & Hyperfine couplings Weakly bound systems & clusters.

Atoms in Molecules: 

Atoms in Molecules