Dissipative tunneling rates through the incorporation of first-principles electronic friction in instanton rate theory. II. Benchmarks and applications

Abstract

In part I, we presented the ring-polymer instanton with explicit friction (RPI-EF) method and showed how it can be connected to the ab initio electronic friction formalism. This framework allows the calculation of tunneling reaction rates that incorporate the quantum nature of the nuclei and certain types of non-adiabatic effects (NAEs) present in metals. In this second part, we analyze the performance of RPI-EF on model potentials and apply it to realistic systems. For a 1D double-well model, we benchmark the method against numerically exact results obtained from multi-layer multi-configuration time-dependent Hartree calculations. We demonstrate that RPI-EF is accurate for medium and high friction strengths and less accurate for extremely low friction values. We also show quantitatively how the inclusion of NAEs lowers the cross-over temperature into the deep tunneling regime, reduces the tunneling rates, and in certain regimes, steers the quantum dynamics by modifying the tunneling pathways. As a showcase of the efficiency of this method, we present a study of hydrogen and deuterium hopping between neighboring interstitial sites in selected bulk metals. The results show that multidimensional vibrational coupling and nuclear quantum effects have a larger impact than NAEs on the tunneling rates of diffusion in metals. Together with part I, these results advance the calculations of dissipative tunneling rates from first principles.

Classical Quantum Friction at Water–Carbon Interfaces

“…While simulation schemes to account for such nonadiabatic dynamics (“electronic friction”) exist, − they rely on the accurate construction of a (3 N × 3 N ) friction tensor, where N is the total number of atoms explicitly considered in the dynamics. So far, their application has been limited to single gas-phase molecules on metal surfaces, − where the friction coefficient on each atom can be well-approximated to depend only on the solid electron density locally. , The low-frequency dielectric modes of water, which are essential to the description of QF, however, are inherently collective in nature, prohibiting the application of these sophisticated methods at present.…”