BDFFRAG is a small tools to generate input for FLMO calculation. BDFFRAG use Gaussian input file prepared from Gview to generate FLMO input automatically for BDF. Connectivity information will be used. There are two methods to generate fragments.

We prefer to extend Gaussian input. Input format:

#HF 3-21G       

Lines of Gaussian input

cutbond    # define which bond will be cut to get atomic groups.
3 C C 1.0 C N 1.5 C O 1.5
centeratoms # define center atoms used to generate molecule fragment via K-mean cluster algorithm
1  5  9  3
radbuff       # define buffer radius, default 2.0
4.5

All additional keywords at the end (cutbond, centeratoms, radbuff) can be omitted; sensible default values will be automatically assigned to them. Even the connectivity information can be omitted as well (but make sure to remove "geom=connectivity" from the Gaussian keyword line); in this case the script automatically deduces the bonding pattern. The usual Gaussian keyword "units=bohr" is respected by the script.

To run command

$BDFHOME/sbin/bdffrag.py inputfile

A file named tmp.inp will be generated. You may modify it by yourself. Call bdffrag.py without command line argument to see more options.

Good luck!