Gygi

Name CurvGygiA
Section Mesh::Curvilinear::Gygi
Type float
Default 0.5

The grid spacing is reduced locally around each atom, and the reduction is given by 1/(1+A), where A is specified by this variable. So, if A=1/2 (the default), the grid spacing is reduced to two thirds = 1/(1+1/2). [This is the $A_{\alpha}$ variable in Eq. 2 of F. Gygi and G. Galli, Phys. Rev. B 52, R2229 (1995)]. It must be larger than zero. It must not be larger than two, as the coordinate transformation is not bijective anymore for larger values of A. This caps the local refinement that can be obtained at 1/(1+2), i.e. a factor of three, which is the governing limitation when attempting all-electron calculations on heavy atoms.

Name CurvGygiAlpha
Section Mesh::Curvilinear::Gygi
Type float
Default 2.0 a.u.

This number determines the region over which the grid is enhanced (range of enhancement of the resolution). That is, the grid is enhanced on a sphere around each atom, whose radius is given by this variable. [This is the $a_{\alpha}$ variable in Eq. 2 of F. Gygi and G. Galli, Phys. Rev. B 52, R2229 (1995)]. It must be larger than zero.

Name CurvGygiBeta
Section Mesh::Curvilinear::Gygi
Type float
Default 4.0 a.u.

This number determines the distance over which Euclidean coordinates are recovered. [This is the $b_{\alpha}$ variable in Eq. 2 of F. Gygi and G. Galli, Phys. Rev. B 52, R2229 (1995)]. It must be larger than zero.