[gmx-users] Qmmm (rose rahmani) (Rose)

[Groenhof, Gerrit]

I live in iran and we don't access to Gaussian.
You think DFTB3 (maybe)could be better choice as it's free?

As I wrote earlier, that depends on whether DFTB3 provides a sufficiently accurate description for your system. To find that out you need to either perform a series of benchmarks, or go through the literature in which the methods has been used successfully for similar systems.