Cholesky-decomposed densities in Laplace-based second-order Moller-Plesset perturbation theory

Based on our linear-scaling atomic orbital second-order Moller-Plesset perturbation theory (AO-MP2) method [J. Chem. Phys. 130, 064107 (2009)], we explore the use of Cholesky-decomposed pseudodensity (CDD) matrices within the Laplace formulation. Numerically significant contributions are preselected using our multipole-based integral estimates as upper bounds to two-electron integrals so that the 1/R(6) decay behavior of transformed Coulomb-type products is exploited. In addition, we combine our new CDD-MP2 method with the resolution of the identity (RI) approach. Even though the use of RI results in a method that shows a quadratic scaling behavior in the dominant steps, gains of up to one or two orders of magnitude vs. our original AO-MP2 method are observed in particular for larger basis sets.