I'm the author and main developer of the Cuby framework, an open-source framework for computational chemistry written in Ruby.
It is a software that allows combining calculations implemented in various external software and construction of complex automated workflows. Cuby is free, cross-platform and easy to install. You can read more on the dedicated website or in my recent paper introducing it.
D3 correction for DFT in small basis set
We have reparameterized the D3 dispersion correction for DFT calculations in small basis set. Among many basis sets tested, the DZVP-DFT basis performs exceptionally well, yielding results similar to these obtained with a triple-zeta basis. Details are described in our recent paper, the parameters are are available on this website.
Corrections for semiempirical methods
The D3H4 corrections for semiempirical methods are now available in MOPAC (for use with the PM6 method), or in the Cuby framework where they can be combined with any method they had been parametrized for. A standalone implementation is also available here.
D3 - dispersion correction can be calculated by the DFT-D3 program developed by S. Grimme (can be obtained ). The parameters for semiempirical methods must be enetered manually, or a patch containing the parameters can be applied to the file dftd3.f (Version 2.1r6). In the latter case, following parameter sets can be selected using the -func option: pm6, rm1, am1, pm3, om3 and scc-dftb.
H4 - hydrogen bonding correction is provided as a single file C program that can be easily compiled on any platform. It implements calculation of energy and gradient (analytic) of the H4 correction and associated hydrogen-hydrogen repulsion. Details on compilation and usage can be found in the source code file.
H5 - hydrogen bonding correction for DFTB is now available in the DFTB+ code along with the version of the D3 correction is should be used with.