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##

Keywords for Modules GRAD and RDGRAD

Many of the `dscf` and `ridft` keywords are also used by
`grad` and `rdgrad`.

$drvopt

This keyword and corresponding options are required in gradient
calculations only in special circumstances.
Just `$drvopt`

is fine, no options needed
to compute derivatives of the energy with respect
to nuclear coordinates within the method specified:
SCF, DFT, RIDFT.

If running a DFT gradient calculation, it is possible to include
the derivatives of the quadrature weights, to get more accurate
results. In normal cases however those effects are marginal. An exception
is numerical calculation of frequencies by `Numforce`, where it is strongly
recommended to use the weight derivatives option.
The biggest deviations from the uncorrected results are to be
expected if doing gradient calculations for elements heavier
than Kr using all electron basis sets and very small grids.
To use the weight derivatives option, add

` weight derivatives`

in `$dft`.

The option

` point charges`

in `$drvopt`

switches on the evaluation of derivatives with
respect to coordinates of point charges. The gradients are written
to the file `$point_charge_gradients`

old gradients will be
overwritten.

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