Structure Optimization in Cartesian Coordinates

For this task you have to specify:

$optimize              
  cartesian on    
  internal  off

These lines switch on the non-default optimization in cartesian coordinates and switch off the optimization in internal coordinates (this has to be done explicitly!). As input data groups you need only $grad as provided by on of the gradient programs. For the first coordinate update an approximate force constant matrix is needed in data group $forceapprox. Output will be the updated coordinates on $coord, and the updated force constant matrix on $forceapprox.

The coordinates for any single atom can be fixed by placing an 'f' in the third to eighth column of the chemical symbol/flag group. As an example, the following coordinates specify acetone with a fixed carbonyl group:

$coord
    2.02693271108611      2.03672551266230      0.00000000000000      c
    1.08247228252865     -0.68857387733323      0.00000000000000      c f
    2.53154870318830     -2.48171472134488      0.00000000000000      o     f
   -1.78063790034738     -1.04586399389434      0.00000000000000      c
   -2.64348282517094     -0.13141435997713      1.68855816889786      h
   -2.23779643042546     -3.09026673535431      0.00000000000000      h
   -2.64348282517094     -0.13141435997713     -1.68855816889786      h
    1.31008893646566      3.07002878668872      1.68840815751978      h
    1.31008893646566      3.07002878668872     -1.68840815751978      h
    4.12184425921830      2.06288409251899      0.00000000000000      h
$end