Smooth potential-energy surfaces in fragmentation-based local correlation methods for periodic systems

Local approximations facilitate the application of post-Hartree–Fock methods in the condensed phase, but simultaneously introduce errors leading to discontinuous potential-energy surfaces. In this work, we explore how these discontinuities arise in periodic systems, their implications, and possible ways of controlling them. In addition, we present a fully periodic Divide-Expand-Consolidate second-order Møller–Plesset approach using an attenuated resolution-of-the-identity approximation for the electron repulsion integrals and a convenient class to handle translation-symmetric tensors in block-Toeplitz format.