  The ground state electronic energy of benzene is the focus of a recent blind
test by Eriksen and co-workers [arXiv:2008.02678]. In this note, we report the
phaseless auxiliary-field quantum Monte Carlo (ph-AFQMC) results on the
identical problem. We examine trial wavefunctions of the spin-restricted
Hartree-Fock (RHF), and complete active space self-consistent field (CASSCF)
with an active space of 6-electron and 6-orbital (i.e., CAS(6,6)) form for the
cc-pVDZ basis set. ph-AFQMC+RHF deviates from the value where many methods
agreed on (i.e., -863 m$E_h$) by -3.1(3) m$E_h$ whereas ph-AFQMC+CAS(6,6)
deviates from the same value by -1.3(4) m$E_h$. In addition to this, we report
the frozen core correlation energy of ph-AFQMC+RHF in the cc-pVTZ and cc-pVQZ
basis sets as well as their complete basis set limit. Our findings highlight
the accuracy, flexibility, and scalability of ph-AFQMC with simple trial
wavefunctions.
