Adf2aim: make input for Xaim (Bader's analysis)

ADF utility adf2aim (original name rdt21) developed by Xavi López, Engelber Sans and Carles Bo (see http://www.quimica.urv.es/ADF_UTIL): convert an ADF TAPE21 to WFN format (for Bader analysis)
The program rdt21 is now called adf2aim and is part of the ADF package, starting from ADF2004.01.

The WFN file is an input file for the third party program Xaim (see http://www.quimica.urv.es/XAIM for details), which is a graphical user interface to programs that can perform the Bader analysis.