LIBINT computes the Coulomb and exchange integrals, which in electronic structure theory are called electron repulsion integrals (ERIs). This is by far the most common type of integrals in molecular structure theory.
LIBINT uses recursive schemes that originate in seminal Obara-Saika method and Head-Gordon and Pople’s variation thereof. The idea of LIBINT is to optimize computer implementation of such methods by implementing an optimizing compiler to generate automatically highly-specialized code that runs well on super-scalar architectures.