Interface to the CFOUR program package (www.cfour.de, free for academic use). CFOUR (Coupled-Cluster techniques for Computational Chemistry) package implements high-level QM calculations. An important feature is the availability of analytic first and second energy derivatives for the coupled clusters methods.
The interface was developed and tested with version 1 of CFOUR. For CCSD and CCSD(T) calculations, externally provided MRCC program can be used.