CFOUR | Main / Interface To MRCC

MRCC is a string-based many-body program written by Mihály Kállay (TU Budapest, Hungary). It is an automated software designed for electronic structure calculations of high complexity such as high-order coupled-cluster (CC) and configuration interaction (CI) methods, multi-reference CC approaches, CC energy derivatives and response functions. Its special feature, the use of strings of molecular orbital indices, enabled the development of tensor manipulation routines which are independent of the number of indices of the corresponding tensors, thus significantly simplifying the general implementation of quantum chemical methods.

Applying the automated tools of the program the following quantum chemistry models and techniques have been implemented so far:

arbitrary single-reference CC and CI methods (CCSD, CCSDT, CCSDTQ, CCSDTQP, ...; CISD, CISDT, CISDTQ, CISDTQP, ...)
general multi-reference CC and CI approaches
analytic first- and second-derivatives for the aforementioned methods
linear and quadratic response functions (i.e., static and frequency-dependent polarizabilities and hyperpolarizabilities) for the aforementioned methods
transition- and first-order excited-state properties for general single- and multi-reference CC models using linear-response CC (LR-CC)/equation-of-motion CC (EOM-CC) formalism
diagonal Born-Oppenheimer correction (DBOC) for arbitrary single-reference CI and CC methods
general approximate CC methods (e.g. CCSD(T), CCSDT(Q), CCSDTQ(P), ...; CCSDT-1, CCSDTQ-1, CCSDTQP-1, ...; CC3, CC4, CC5, ...; CCSDT-3, CCSDTQ-3, CCSDTQP-3, ...

The MRCC code is available from the author upon request. For more information see www.mrcc.hu.