Liquid-state polaron theory of the hydrated electron revisited

TL;DR

This paper revisits the liquid-state polaron theory for the hydrated electron, improving its accuracy by incorporating advanced approximations and comparing predictions with simulation data, revealing both strengths and limitations of the model.

Contribution

The study introduces the use of RO-RPA and DRL approximations into the polaron theory for the hydrated electron, enhancing its predictive accuracy and comparing it with simulation results.

Findings

RO-RPA and DRL approximations yield similar, improved predictions.

The theory's predictions align reasonably with simulation data for most properties.

The solvation free energy predictions are significantly higher than experimental values.

Abstract

The quantum path integral/classical liquid-state theory of Chandler and co-workers, created to describe an excess electron in solvent, is re-examined for the hydrated electron. The portion that models electron-water density correlations is replaced by two equations: the range optimized random phase approximation (RO-RPA), and the DRL approximation to the "two-chain" equation, both shown previously to describe accurately the static structure and thermodynamics of strongly charged polyelectrolyte solutions. The static equilibrium properties of the hydrated electron are analyzed using five different electron-water pseudopotentials. The theory is then compared with data from mixed quantum/classical Monte Carlo and molecular dynamics simulations using these same pseudopotentials. It is found that the predictions of the RO-RPA and DRL-based polaron theories are similar and improve upon previous theory, with values for almost all properties analyzed in reasonable quantitative agreement with the available simulation data. Also, it is found using the Larsen, Glover and Schwartz pseudopotential that the theories give values for the solvation free energy that are at least three times larger than that from experiment.