Calculation of Metallocene Ionization Potentials via Auxiliary Field Quantum Monte Carlo: Towards Benchmark Quantum Chemistry for Transition Metals

The accurate ab initio prediction of ionization energies is essential to understanding the electrochemistry of transition metal complexes in both materials science and biological applications. However, such predictions have been complicated by the scarcity of gas-phase experimental data, the relatively large size of the relevant molecules, and the presence of strong electron correlation effects. In this work, we apply all-electron phase-less auxiliary-field quantum Monte Carlo (ph-AFQMC) utilizing multi-determinant trial wavefunctions to six metallocene complexes to compare the computed adiabaticand vertical ionization energies to experimental results. We find the ph-AFQMC mean averaged errors (MAE) of 1.69±1.02 kcal/mol for the adiabatic energies and 2.85±1.13 kcal/mol for the vertical energies. This significantly outperforms density functional theory (DFT), which has MAE’s of 3.62 to 6.98 and 3.31 to 9.88 kcal/mol, as well as a localized coupled cluster approach (DLPNO-CCSD(T0) with moderate PNO cut-offs), which has MAEs of 4.96 and 6.08 kcal/mol, respectively. We also test the reliability of DLPNO-CCSD(T0) and DFT on acetylacetonate (acac) complexes for adiabatic energies measured in the same manner experimentally, and find higher MAE’s, ranging from 4.56 kcal/mol to 10.99 kcal/mol (with a different ordering) for DFT and 6.97 kcal/mol for DLPNO-CCSD(T0), indicating that none of these approaches can be considered benchmark methods, at least for these complexes. We thus demonstrate that ph-AFQMC should be able to handle metallocene redox chemistry with the advantage of systematically improvable results. By utilizing experimental solvation energies, we show that accurate reduction potentials in solution can be obtained.

Remote Geotechnical Evaluation of Rights of Way of Hydrocarbon Transmission Lines

Due to the health emergency currently affecting the planet, it has been impossible for engineering specialists to carry out direct inspections of the land. During this time, it has been necessary to develop techniques and procedures that allow engineers to obtain information from the land remotely. Here, they are supported by the technology that allows them to record images remotely via drones and communicate so they can perform inspections by auxiliary field personnel, directed at a distance by specialists. To do this, a preliminary flight plan is defined, based on the experience and knowledge of the terrain by the specialist and the visual of the drone is transmitted via the Internet from a PC in the field. Later, which images to record and the sites that require more detail or a direct inspection by the field assistant are defined. Finally, the field assistant transmits the images of the inspection. In this way, the specialist’s training and experience, the operational ease of the drone, and the skill of the field staff are taken advantage of. This article details the procedure for remote inspection, and ways in which it can even be extended to corridor recognition tasks to define the layout of rights of way.

The 300 “correlators” suggests 4D, $$ \mathcal{N} $$ = 1 SUSY is a solution to a set of Sudoku puzzles

A conjecture is made that the weight space for 4D, $$ \mathcal{N} $$ N -extended supersymmetrical representations is embedded within the permutahedra associated with permutation groups 𝕊d. Adinkras and Coxeter Groups associated with minimal representations of 4D, $$ \mathcal{N} $$ N = 1 supersymmetry provide evidence supporting this conjecture. It is shown that the appearance of the mathematics of 4D, $$ \mathcal{N} $$ N = 1 minimal off-shell supersymmetry representations is equivalent to solving a four color problem on the truncated octahedron. This observation suggest an entirely new way to approach the off-shell SUSY auxiliary field problem based on IT algorithms probing the properties of 𝕊d.