The Massively Parallel Quantum Chemistry (MPQC) package has two components:

a set of C++ libraries intended for use in molecular electronic structure (aka quantum chemistry, QC), and
the end-user program for performing QC computations. The former is of interest to the developers of QC (and other) software, whereas the latter is of interest to those wishing to use the standard QC methods for practical computations.

The software developers using MPQC will primarily be interested in the QC-specific C++ libraries, known collectively as mpqc.Chemistry; these libraries can be used to implement existing and new QC methods easily. In turn, mpqc.Chemistry libraries are supported by two sets of C++ libraries:

mpqc.Core, also known as the Scientific Toolkit (SC) in the past: core libraries for managing memory, saving and restoring the state of objects, reading objects from an input file, parallel communication, among others.
mpqc.Math: libraries for data containers (matrix and multidimensional array/tensor) and associated algebra, such as solving linear and nonlinear equations expressed in terms of these data containers.

The MPQC program is the end-user code for practical application of the variety of quantum chemistry methods implemented using mpqc.Core. Although MPQC lacks many features demanded by many mainstream users of quantum chemistry, it can be used by non-experts for applications of routine (Hartree-Fock, Density Functional Theory, MP2) as well as some unique advanced quantum chemistry methods (explicitly-correlated coupled-cluster and multireference methods). MPQC is also suitable for learning quantum chemistry by advanced undergraduate and beginning graduate students. Lastly, MPQC includes unique emerging functionality that is not yet accessible by non-experts.

Although the development of MPQC has been ongoing since 1993, the code is constantly evolving. MPQC is fundamentally an experimental/research code that is used to seek new computational approaches to problems in scientific programming in general and, in particular, to quantum chemistry. Thus, this manual is incomplete. Furthermore, some of the classes in the distribution may be on the verge of obsolescence and others may be unfinished work that are intended to provide new functionality in later releases.

MPQC runs on Unix platforms of all kinds, from a laptop running Linux or Apple OS X to a basic lab-scale Unix cluster to a high-end supercomputer such as IBM BlueGene/Q.