All-electron first-principles GWΓ simulations for accurately predicting core-electron binding energies considering first-order three-point vertex corrections

In the conventional GW method, the three-point vertex function (Gamma) is approximated to unity (Gamma similar to 1). Here, we developed an all-electron first-principles GW Gamma method beyond a conventional GW method by considering a first-order three-point vertex function (Gamma((1)) = 1 + iGGW) in a one-electron self-energy operator. We applied the GW Gamma method to simulate the binding energies (BEs) of B1s, C1s, N1s, O1s, and F1s for 19 small-sized molecules. Contrary to the one-shot GW method [or G(0)W(0)(LDA)], which underestimates the experimentally determined absolute BEs by about 3.7 eV for B1s, 5.1 eV for C1s, 6.9 eV for N1s, 7.8 eV for O1s, and 5.8 eV for F1s, the GW Gamma method successfully reduces these errors by approximately 1-2 eV for all the elements studied here. Notably, the first-order three-point vertex corrections are more significant for heavier elements, following the order of F > O > N > C > B1s. Finally, the computational cost analysis revealed that one term in the GW Gamma one-electron self-energy operator, despite being computationally intensive, contributes negligibly (<0.1 eV) to the C1s, N1s, O1s, and F1s.