Comparison of two efficient approximate Hartee–Fock approaches

The efficiency of two approximate Hartree–Fock approaches was benchmarked. Weigend’s RI-JK algorithm is compared to the recently developed RIJCOSX technique in terms of accuracy and total wall clock times. Both methods reproduce the canonical results within the chemical accuracy of ∼kcalmol−1. RI-JK turns out to be more robust than RIJCOSX due to an overall positive error in the total energies. However, RIJCOSX outperforms RI-JK regarding speed-ups for the largest (gly)8 chain and maintains comparable accuracy.