All AFQMC calculations were carried out using single determinant trial wavefunctions as detailed in Ref. 41. The trial wavefunctions (UB3LYP) and integrals for AFQMC were obtained with PySCF v2.0. Similar to previous studies, the imaginary time step for the AFQMC propagation was 0.005 Ha -1 , and the total propagation time was 200 Ha -1 , employing the "comb" algorithm for population control every 20 steps. We used 3312 total walkers, which were initialized with a spin-restricted HF determinant.