Troubleshooting

• 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)