The utility rafbas

The utility $ADFBIN/rafbas.exe reads its input from the local file 'raf_in' and writes its output to the local file 'et_in'. No further user input is required. This utility basically transforms the answers of the user to the questions posed in 'questbas' into a set of N, α, β values for both the basis and the fit.

The rafbas and the other utilities were originally also intended for generating so-called cusp-satisfying basis sets, which consist of (for the s functions) 1 1s functions to which ET 3s functions are added. However, some tests indicated that the core description of these basis sets, which was supposed to be very good, did not improve upon those of the normal ET basis sets and therefore the cusp-satisfying basis sets were abandoned.

The rafbas utility contains information about the beta values for the fit. For the default 'VERYLARGEFIT' option, the beta values were chosen such that the overlap between two successive fit functions does not exceed 0.95 for s and 0.90 for higher l it functions. Earlier experience with generating fit sets led to the conclusion that even larger fit sets have a large risk of becoming linearly dependent which causes numerical problems. The rafbas utility also adds the polarization function exponents. It contains a list of 'best' exponents for many elements. It further more handles the options to extend the basis by decreasing beta and to add first- and second-order FIPs (field-induced polarization functions) for the generation of basis sets for (hyper)polarizability calculations.