The performance of phaseless auxiliary-field quantum Monte Carlo on the ground state electronic energy of benzene

Researchers examine the accuracy of phaseless auxiliary-field quantum Monte Carlo (ph-AFQMC) on the identical problem. ph-AFQMC is a method that has prominently featured in several benchmark studies led by the Simons Collaboration and has stood out as a flexible and state-of-the-art ab initio approach. The choice of trial wavefunction wholly determines the accuracy of ph-AFQMC. It is possible to exploit multi-determinant (MD) trial wavefunctions and observe a convergence of the ph-AFQMC energy with respect to the number of determinants. The researchers also report the ph-AFQMC + RHF correlation energies on larger basis sets (cc-pVTZ and cc-pVQZ) along with the extrapolated complete basis set limit correlation energy. They believe that due to the accuracy, flexibility, and scalability of the approach, the addition of ph-AFQMC results to those of the recent blind test will contribute to the informed use of a broad set of methods to tackle diverse electronic structure problems.