python dftd3.py (-damp zero/bj) (-s6 val) (-rs6 val) (-s8 val) (-a1 val) (-a2 val) (-im on/off) (-pw on/off) file(s)
This program will compute the D3-dispersion energy, as developed by Grimme and colleagues, for one or a series of Gaussian-formatted input or output file(s) in Cartesian coordinates. The dispersion energies will be identical to those produced by the original Fortran version of dftd3, or from the Gaussian program itself, provided the same damping parameters are used. This version implements both versions of short-range damping that appear in the literature (namely zero-damping and Becke-Johnson damping) provided the required parameters are specified manually, or the density functional is recognized from the input file - in which case default values will be used. This program was developed to analyze interatomic and intermolecular dispersion energies within the D3-scheme: if two molecules are recognized based on the interatomic connectivity then it is possible to ignore intramolecular terms.
If a density functional is not recognizable from the input/output file it will be necessary to specify the desired damping parameters. For zero-damping three (S6, S8 and RS6) are required and for Becke-Johnson damping four (S6, S8, A1, A2) are required.
The 3-body Axilrod-Teller-Muto 3-body dispersion terms can be switched on (they are not computed by default) with the flag
The type of damping can be switched from Becke-Johnson (the default) to Zero with the flag
To view the pairwise contribution of all dispersion terms
-pw on (default is off)
To view only the intermolecular dispersion energy
-im on (default is off, and requires the interatomic connectivity information to be specified in an input file so that there are two separate molecules)
- Specifying B3LYP params for an input file rpaton$ python eval_D3.py 1.0 1.261 1.703 CH3F.com
s6 = 1.0 rs6 = 1.261 s8 = 1.703 Breakdown Attractive-R6 Attractive-R8 Repulsive-3-Body Total (Hartree) CH3F.com -1.92973198055e-05 -0.000722345327786 2.55309958043e-07 -0.000741387337633
- B3LYP outfile - params don't matter as the script will figure it out (hopefully) - only works with a few functionals rpaton$ python eval_D3.py 1 1 1 CH3F2TS.log
o Using default B3LYP D3 parameters: s6 = 1.0 rs6 = 1.261 s8 = 1.703 Breakdown Attractive-R6 Attractive-R8 Repulsive-3-Body Total (Hartree) CH3F2TS.log -0.000123819933174 -0.00219749682351 5.61353002398e-07 -0.00232075540368