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Structure Optimizations Using Internal Coordinates

This is the default task of relax ($optimize internal on does not need to be specified!) You need as input the data groups :
$grad
cartesian coordinates and gradients as provided and accumulated in subsequent optimization cycles by the programs grad, or rdgrad etc.
$intdef
definitions of internal coordinates.
$redundant
definitions of redundant coordinates.
Output will be the updated coordinates on $coord and the updated force constant matrix on $forceapprox. If any non-default force constant update option has been chosen, relax increments its counting variables <numgeo>, <numpul> within command keyword $forceupdate. If the approximate force constant has been initialized ($forceinit on ) relax switches the initialization flag to $forceinit off. Refer also to the general documentation of TURBOMOLE. It is recommended to check correctness of your definition of internal coordinates:
  1. Calculate their values for your cartesian start coordinates using the relax program (see Section 5.3.11) or within a define session.
  2. Have a look at the eigenvectors of the BmB-matrix. Set some `?' behind keyword $intdef, if there are any eigenvalues close to zero ( < 10-2 is to be considered bad for small molecules, but there is no general rule) check those internal coordinates for consistency which contribute to the corresponding eigenvector(s)!


next up previous contents index
Next: Structure Optimization in Cartesian Up: Program Relax Previous: Definition of Internal Coordinates   Contents   Index
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