Accuracy and Efficiency

Given a chosen model Hamiltonian (discussed elsewhere), the three main issues that influence the accuracy of a calculation are: integration in real space, integration in reciprocal space, and the quality of the basis set.

General Numerical Quality

The key NumericalQuality sets the quality of several important technical aspects of a BAND calculation (with the notable exception of the basis set)

NumericalQuality [Basic | Normal | Good | VeryGood | Excellent]

NumericalQuality

(Default: Normal) This key sets the default Quality of the Becke grid, ZlmFit, k-space integration, and SoftConfinement. Possible values are Basic, Normal, Good, VeryGood, and Excellent. For the user this is the most convenient way to influence the precision, and estimate the error. It is always possible to tweak things more, as is explained below.

Defaults Convention

There has been a big change in many default settings with the 2014 release. To switch between the two styles

DefaultsConvention [Pre2014 | 2014]

With the pre2014 settings, you will get STO fitting, the Voronoi grid, the old, symmetric k-point sampling, and no confinement, resembling the behavior of the 2013 version.

• Basis set
  • Automatic mode: BasisDefaults
  • Available standard basis sets
  • Manually specifying AtomTypes
  • Confinement of basis functions
• Real Space Numerical Integration
  • Becke Grid
  • Radial grid
  • Elliptic integrals
  • Voronoi grid (deprecated)
• Reciprocal Space Numerical Integration (KSpace)
  • Regular K-Space grid
  • Tetrahedron Method
• Density fitting
  • Zlm Fit
  • Obsolete Method - STO Fit
• Self-consistency
  • SCF key
  • Convergence key
  • DIIS key
  • DIRIS key
• Hartree–Fock RI scheme
• Technical Settings
  • Linear Scaling
  • Dependency
  • Screening
  • Direct (on the fly) calculation of basis and fit
  • Fermi energy search
  • Block size