Density Functional Theory at the Basis Set Limit with Multiwavelets

Abstract

The mainstream approaches to represent orbitals in wave function theory and DFT are indubitably Gaussian Type Orbitals (GTOs) and plane waves (PWs) for isolated and periodic systems respectively. Such choices are inherited from a not so distant past when computational resources were much scarcer and it was mandatory to provide the most compact representation possible. Current computational resources open the way to real-space grid approaches such as multiwavelets. We show how, by making use of multiwavelets, unprecedented and -- most importantly -- controlled accuracy can be achieved for energy and properties. The approach is in principle also very well suited to harvest modern computational architectures, based on large distributed clusters. The main challenges for such an approach are represented by the memory requirements the "curse of dimensionality", which limit at present the approach to small systems (100 electrons or less) and single-determinant methods (HF and DFT). In this contribution we present briefly main ideas about the Multiwavelet approach and our recent results about energy and properties of molecules.