The spacing between the points in the mesh. This controls the
quality of the discretization: smaller spacing gives more
precise results but increased computational cost.
When using curvilinear coordinates, this is a canonical spacing
that will be changed locally by the transformation. In periodic
directions, your spacing may be slightly different than what
you request here, since the box size must be an integer
multiple of the spacing.
The default value is defined by the species if only default pseudopotentials are used
or by the image resolution if BoxShape = box_image. Otherwise, there is
It is possible to have a different spacing in each one of the Cartesian directions
if we define Spacing as block of the form