Separable form

Norm-conserving pseudopotentials generated by the BHS and TM schemes are written in a semi-local form which is based on a projection by the spherical harmonic function. In the application of pseudopotentials to molecules and bulks, the semi-local form is rewritten by a fully separable form proposed by Kleinman and Bylander (KB) [7], or Blöchl [8], to reduce the computational effort. Then, the following keywords are important for transferability of the separable form.

• Blochl.projector.num

  The number of Blöchl projectors for each L-component in separable pseudopotentials. If you specify 1 for Blochl.projector.num, this means the Kleinman and Bylander (KB) separable pseudopotentials.

• local.type

  'Simple' and 'Polynomial' are available.

• local.part.vps

  Number of local potential in case of local.type=Simple

• local.cutoff

  The cutoff radius of local part in case of local.type=Polynomial

• local.origin.ratio

  Depth of local part at the origin in case of local.type=Polynomial

Although the MBK scheme also constructs a separable form in a different way, the proper selection of above the keywords is important as well. You can find details for these keyword in the section, Input file.