For many years the performance of scientific softwares has been one of the keys to expand the frontiers of science. The case of Computational Chemistry is not an exception. Quantum chemists all around the world have worked intensively to produce faster and more efficient software in order to be able to study bigger and more complex systems. Hartree-Fock (HF) molecular orbital theory is one of the fundamental pillars of Quantum Chemistry, and as such, it has been in development for many years. This constant development includes improved algorithms to accelerate the self consistent field (SCF) convergence, more efficient algorithms to perform integration, and lately, the implementation of all those algorithms using parallel techniques, such as, MPI (Message Passing Interface), OpenMP (Open Multi-Processing), CUDA, among others. Nowadays, HF can be applied to molecules containing hundreds of atoms in commodity computers.
Discussion on HF theory is not the main goal of this work, but let us to recall some of the HF equations that are needed to illustrate the work done here. More detailed information on HF theory can be found in reference.