Editing G09 (section)

== Dispersion ==

'''In revisions before G09.D1:''' One of the new features in Gaussian G09, is the possibility to include dispersion. This can be done in two different ways.

* By using the B97D functional, which includes dispersion. With this you can optimize or do single point calculations.

* With the iop: iop(3/124=3),which allows to compute the Dispersion on a given structure optimized at  your favourite level of theory (to add Dispersion as single point). The good point of this is that can be done using any set of basis and method (using SDDall you can save lot's of computer time).

The issue is that the first and second revision of Gaussian A1 and A2 do NOT perform the Dispersion calculation properly. You need the revision B1 (not in kimik2 look at cesca).

'''For revision G09.D1:''' There are different ways of including dispersion:

* By using B97D or B97D3

* By using the keyword EmpiricalDispersion = and choosing a dispersion model