Optim

GEOMETRY
 Optim {Delocal/ Cartesian / Internal } {All / Selected}
..
END

Optim

Delocal

Optimization in delocalized coordinates (Delocal) is the default in geometry optimizations, transition state searches, and (linear) transits. Starting from ADF2007 with delocalized coordinates you can use constraints (see also CONSTRAINTS key) and restraints, and you can supply the atoms in Z-matrix coordinates. You can not use dummy atoms, ghost atoms, or alternative elements. Starting from ADF2007 the adapted delocalized coordinates are used as described in Ref. [225].

Cartesian / Internal

Cartesian or Zmatrix (equivalently: internal) specifies the type of coordinates in which the minimization is carried out. By default the coordinate type is applied that was used in the ATOMS key for the input of the (initial) atomic positions. (Cartesian if atoms were input in zcart format). Note that Zmatrix optimizations can only be done with the old branch of optimizations.

Cartesian optimization is allowed if the atoms were input in Z-matrix format, but no constraints (see the key GEOVAR) can then be used: all coordinates are optimized. An attempt to explicitly freeze variables may result in an error abort. Optimization in Z-matrix coordinates is not allowed if only Cartesian coordinates were supplied in atoms: the program does not construct a Z-matrix by itself. One should then use the zcart format: give Cartesian coordinates and supply the structure of the Z-matrix. Again, in this case you cannot use constraints.

Selected

For use with old branch of optimizations. Only those coordinates are optimized that are defined with the key GEOVAR.

All

(The default value) means that in principle all atomic coordinates will be varied. With the new branch of optimization the key CONSTRAINTS one may set constraints on the optimization. With the old branch of optimization one can use the key GEOVAR to set constraints.