Topic: DFT, scripting in Python

Download these files. Be prepared: Gaussian is needed

Lecture slides

Practice (selectively)

  • Estimate the dipole moment of CO molecule using different approaches [diatomic]
    • Investigate basis set convergence
    • Investigate MP convergence
    • Investigate CI and CC convergence
    • Investigate density functional dependence. Can we say that LDA "over-delocalizes" electron density and HF "over-localizes" it?
    • Compare with experimental data and other calculations (see CCCBDB)
    • The same for equilibrium bond length, force constant, and dipole moment derivative
    • Analyze methods in terms of computing time
  • Dynamic correlations in CO molecule [diatomic]
    • Compare MO and NO of CO molecule
    • Analyze NO occupations
    • Explain absence of basis set convergence for small virtual space CI
  • What is the difference between bonding in CO and H2CO molecules? Compare charge distribution. Draw orbital interaction diagram
  • Investigate density functional dependence of the ionization potential of ethylene molecule [ethylene_IPEA]
  • Observe Koopmans' theorem violation in approximate DFT [benzene_IP.txt]
  • SCF convergence problems related to wrong initial guess [NDI]
    • Calculate adiabatic IP for thiophene by CAM-B3LYP/6-31G*
    • Calculate cation NO for NDI molecule with CAM-B3LYP and compare it with HOMO
    • Analyze initial guess for MOs and correct it
    • Why there is no such artefact for another conformer of NDI molecule (molec-a)
    • Check if no-symmetry keyword will help
    • Why there is no such artefact for B3LYP
    • Solvate both ground and excited cation states in water
  • Computational artifacts:

Reading

  • Cramer chapter 8
  • Jensen chapter 6
  • Burke: The ABC of DFTTutorial slidesReview 2012
  • K Lejaeghere etal, Reproducibility in density functional theory calculations of solids, Sci 351, 1415 (2016)
  • J Witte, J B Neaton, M Head-Gordon, Push it to the limit: Characterizing the convergence of common sequences of basis sets for intermolecular interactions as described by density functional theory, JCP 144, 194306 (2016)