Section Calculation Modes::Geometry Optimization
If XYZGOConstrains, PDBConstrains, and XSFGOConstrains are not present, Octopus will try to fetch the geometry optimization contrains from this block. If this block is not present, Octopus will not set any constrains. The format of this block can be illustrated by this example:
‘C’ | 1 | 0 | 0
‘O’ | 1 | 0 | 0
Coordinates with a constrain value of 0 will be optimized, while coordinates with a constrain different from zero will be kept fixed. So, in this example the x coordinates of both atoms will remain fixed and the distance between the two atoms along the x axis will be constant.
Note: It is important for the constrains to maintain the ordering
in which the atoms were defined in the coordinates specifications.
Moreover, constrains impose fixed absolute coordinates, therefore
constrains are not compatible with GOCenter = yes