Basis set (Basis on the radial grid) files

Basis files have a fixed format. The files generated from the trex2champ converter can also be used as they are. These files are generally kept in the pool directory of the calculation folder. You just need to specify the name of the basis file (say, ccpVTZ) in the general module of CHAMP input file under the keyword basis. This will read the file ccpVTZ.basis.Si for the element Si.

The top few lines of BFD-T.basis.C look like

9 3 2000 1.003000 20.000000 0
 0.000000000000e+00  5.469976184517e-01  2.376319920758e+00  5.557936498748e-01  3.412818210005e+00  2.206803021951e-01  8.610719484857e-01  3.738901952004e-01  3.289926074834e+00  1.106692909826e+00
 1.508957441883e-04  5.469976454488e-01  2.376319870895e+00  5.557936481942e-01  3.412817957941e+00  2.206803015581e-01  8.610719410992e-01  3.738901923954e-01  3.289925989316e+00  1.106692890335e+00
 ...

This means there are 9 radial shells in the basis set of carbon put on a radial grid of 2000 points (upto 20 bohr).

Basis set files are sourced from the pool directory. All unique atoms should have a corresponding basis file.