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:
- Often we have to apply methods beyond their validity (because usually we solve mathematically ill-defined problems) ⇒ use multiple methods
- Madelung constant
- Nonplanarity of benzene (Moran2006, Lawler2008, Walewski2014 vs Shishkin2011)
- see CCCBDB for other examples

## Reading

- Cramer chapter 8
- Jensen chapter 6
- Burke: The ABC of DFT, Tutorial slides, Review 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)