We discuss computational methods for carrying out correlated ab initio electronic structure calculations for large systems. The focus is on two types of methods: density functional theory (DFT) and localized orbital methods such as local MP2 (LMP2) and a multireference version based upon a generalized valence bond reference wave function, GVB-LMP2. The computational performance of both approaches using pseudospectral numerical methods is documented, and calculated thermochemical and conformational energetics are compared to experimental data.