Optimization of Structure and a Global Scaling Factor

Optimization of a global scaling factor is usually not performed in geometry optimizations. It is a special feature for special applications by even more special users. As reference see [33].

To optimize the structure and a global scaling factor specify:

$optimize              
  internal  on   (or: cartesian on)
  global    on

You need as input data groups $grad and $globgrad, the latter contains the global scaling factors and their gradients accumulated in all optimization cycles. Output will be on $coord, $global, also on $forceapprox (updated). Note that for optimization of a global scaling factor a larger initial force constant element is recommended (about 10.0).