optimisation from hessian

[monika]

Hello
I would like ask you how can I start optimisation (ri-mp2) from hessian optimized DFT. Which method will be the bast.
My strukture  has 30 atmos, 440 basis functions, it's open shell. Please for answer.

best regards

[turbomaster]

Hello

It is possible to use a calculated Hessian matrix for structure optimizations.

1. When using Jobex/Relax combination you have to modify the $forceinit section
of the "control" file to
$forceinit
   carthess
Additionally, if you use internal coordinates you have to activate the conversion
of force constants matrix from Cartesian to internals by specifying
$interconversion on
   cartesian --> internal  hessian
in the "control" file.
The details are also described in the TM manual under
"Calculation of Molecular Structure and Ab Initio Molecular Dynamics"

2. In the Jobex/Statpt combination the calculated Hessian matrix will
automatically be used if any of the sections $hessian, $hessian (projected),
or $nprhessian is present in the "control" file.