In the last decade quantum chemistry has developed to a stage where it is capable of providing molecular properties with quantitative accuracy. The development of efficient electronic-structure methods enabled calculations with chemical ($\sim$1 kcal/mol) or even higher precision for small to medium-sized molecules. In this talk we will discuss the possibilities to extend the applicability of accurate quantum chemical methods beyond the scale accessible to current techniques, to develop quantum chemical methods that are applicable to large molecules and simultaneously provide sufficiently accurate results. This goal can be achieved through the use of local correlation approximations, which utilize the fact that the short-range correlation interaction of electrons decays rapidly with their distance. Our new local coupled-cluster (CC) and random-phase approximation (RPA) algorithms will be presented, which help us to achieve linear scaling for the computational expenses with the system size and are applicable to molecules of hundreds of atoms. We will demonstrate the applicability of our methods for real-life problems.

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