Use of approximate integrals in ab initio theory. An application in MP2 energy calculations

Abstract

We use the resolution of the identify (RI) as convenient way to replace the use of four-index-two-electron integrals with linear combinations of three-index integrals. The method is broadly applicable to a wide range of problems in quantum chemistry. We demonstrate the effectivenes of RI for the calculation of MP2 energies. For the water dimer, agreement within 0.1 kcal/mol is obtained with respect to exact MP2 calculations. The RI-MP2 energies require only about 10% of the time required by conventional MP2.