Troubleshooting
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* Recommendations

  * Model Hamiltonian

  * Technical Precision

  * Performance

  * Band gap calculations

* Troubleshooting

  * SCF does not converge

  * Geometry does not converge

  * Lattice optimization does not converge for gga

  * I see two band gaps, which one is best?

  * Band structure does not match the DOS

  * Missing core bands or DOS peaks in amsbands

  * Negative frequencies in phonon spectra

  * Too much scratch disk space is used

  * Basis set dependency

  * Frozen core too large

  * requested kgrid appears to break the symmetry

* Various issues

  * Understanding the logfile

  * Breaking the symmetry

  * Labels for the basis functions

  * Reference and Startup Atoms

  * Numerical Atoms and Basis functions

* Warnings

  * Warnings specific to periodic codes (BAND, DFTB)
