## Sunday, March 18, 2012

### A consistent and accurate ab initio parametrization of density functional dispersion correction (DFT-D) for the 94 elements H-Pu

S. Grimme, J. Antony, S. Ehrlich, and H. Krieg Journal of Chemical Physics 2010, 132, 154104 (Paywall)

With 245 Web of Science citations this paper by Grimme and co-workers must be one of the most cited density functional paper published recently.  The dispersion correction to DFT is based on average atomic dipole polarizability tensors at imaginary frequency computed for 227 representative hydrides of the first 94 elements.  These polarizability tensors are computed using TD-DFT using the PBE38 functional and a doubly augmented def2-QZVP basis set.  Hydrides with different atomic hybridization are included to yield hybridization-specific dispersion energies and an interpolation method handles atoms judged to have intermediate hybridization.

The correction consists of $r^{-6}$ and $r^{-8}$ two-body terms and an $r^{-9}$ three-body term, which are all damped at short-range using a damping function.  The method contains a total of two adjusted parameters, which are obtained by fitting to conformational and interaction energies computed using CCSD(T)/CBS for several structural datasets.  Optimized parameters are presented for 11 different functionals.

The method, termed DFT-D3, typically achieves an accuracy that is within 10% of CCSD(T) results based on the data presented in the paper.  However, higher errors were observed for "some chemical reaction energies, in particular those involving many carbon atoms."

A FORTRAN implementation has been made freely available, and the method is already implemented in several software packages such as GAMESS and ADF.