DFT-D3 settings compared to original code of the Grimme group

[uwe]

Dear Turbomole users,

the chapter in the manual about dispersion corrections for DFT lacks some important information.

The $disp3 keyword enforces the usage of Grimme's original DFT-D3 code. This code can be downloaded and used from the author's website, http://www.thch.uni-bonn.de/tc/index.php?section=downloads&subsection=DFT-D3&lang=english. This stand-alone version named dftd3 can be used as an add-on to Turbomole calculations and comes with a couple of options.

In Turbomole, those original routines are used, and the command line arguments of the stand-alone version can be added to the $disp3 keyword. For example:

dftd3 coord -bj

in the original code gives the same as

$disp3 bj

in the Turbomole control file. Or $disp3 -bj, Turbomole ignores the minus in this case.

There are, however, some differences:

• for gradient runs, the option -grad is not needed and automatically applied, so for geometry optimizations a naked $disp3 is sufficient.
• the name of the DFT functional (-func) is also not needed since Turbomole knows which functional is used from the input.
• vibrational frequencies with $disp3 also automatically include the DFT-D3 terms.

Regards,

Uwe