Efficient evaluation of three-center two-electron integrals over Gaussian functions
The RI (resolution of the identity) technique achieves significant increases in efficiency for various molecular electronic structure methods. This results from the approximation of four-center two-electron integrals by corresponding three-center integrals. It is shown that the three-center integrals required can be evaluated with a much simpler algorithm than for the general case. This further increases the advantage of RI procedures.