Accurate simulation of weakly-Bound Dipole Anions

We currently demonstrated that quantum Monte Carlo (QMC) techniques accurately predict dipole-bound anions. First theorized to exist by Fermi, dipole-bound anions are molecules that possess dipoles sufficiently strong to trap a loosely-bound electron. They can be thought of as the anionic counterparts of the Rydberg atoms. From the theoretical standpoint, modeling/predicting dipole-bound anions is particularly challenging because the energies with which they bind electrons are incredibly small: binding energies of 10-200 cm-1 make the difference between molecules that can bind electrons and those that cannot. Methods capable of describing these species must therefore deliver <10cm-1 accuracies at costs manageable for large aromatic molecules, a central challenge for any electronic structure method. With our simulations on a variety of dipole bound species, we have demonstrated that QMC methods (including variational, diffusion and auxiliary field monte carlo) can reproduce experimental binding energies with accuracy equal to or even better than more computationally demanding quantum chemistry methods such as CCSD.