Generation of optimized FORTRAN code for molecular integrals of Gaussian-type functions

The calculation of molecular properties based on quantum mechanics is an area of fundamental research whose horizons have always been determined by the power of state-of-the-art computers. A computational bottleneck is the numerical calculation of molecular integrals to sufficient precision. Herein, we present a method for the rapid numerical evaluation of molecular integrals using optimized FORTRAN code generated by Maple. The method is based on the exploitation of common intermediates and the optimization can be adjusted to both serial and vectorized computations. In the particular application shown here, the greatest computational reductions resulted from the exploitation of hidden structures within the molecular integrals.