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Title: Free energy functionals for polarization fluctuations: Pekar factor revisited

The separation of slow nuclear and fast electronic polarization in problems related to electron mobility in polarizable media was considered by Pekar 70 years ago. Within dielectric continuum models, this separation leads to the Pekar factor in the free energy of solvation by the nuclear degrees of freedom. The main qualitative prediction of Pekar’s perspective is a significant, by about a factor of two, drop of the nuclear solvation free energy compared to the total (electronic plus nuclear) free energy of solvation. The Pekar factor enters the solvent reorganization energy of electron transfer reactions and is a significant mechanistic parameter accounting for the solvent effect on electron transfer. Here, we study the separation of the fast and slow polarization modes in polar molecular liquids (polarizable dipolar liquids and polarizable water force fields) without relying on the continuum approximation. We derive the nonlocal free energy functional and use atomistic numerical simulations to obtain nonlocal, reciprocal space electronic and nuclear susceptibilities. A consistent transition to the continuum limit is introduced by extrapolating the results of finite-size numerical simulation to zero wavevector. The continuum nuclear susceptibility extracted from simulations is numerically close to the Pekar factor. However, we derive a new functionality involvingmore » the static and high-frequency dielectric constants. The main distinction of our approach from the traditional theories is found for the solvation free energy due to the nuclear polarization: the anticipated significant drop of its magnitude with increasing liquid polarizability does not occur. The reorganization energy of electron transfer is either nearly constant with increasing the solvent polarizability and the corresponding high-frequency dielectric constant (polarizable dipolar liquids) or actually noticeably increases (polarizable force fields of water).« less
ORCiD logo [1] ;  [2] ; ORCiD logo [3]
  1. School of Molecular Sciences, Arizona State University, P.O. Box 871604, Tempe, Arizona 85287-1604, USA
  2. Chemistry Department, Brookhaven National Laboratory, P.O. Box 5000, Upton, New York 11973-5000, USA
  3. Department of Physics and School of Molecular Sciences, Arizona State University, P.O. Box 871504, Tempe, Arizona 85287-1504, USA
Publication Date:
Report Number(s):
Journal ID: ISSN 0021-9606; JCPSA6
Grant/Contract Number:
SC0015641; SC00112704
Accepted Manuscript
Journal Name:
Journal of Chemical Physics
Additional Journal Information:
Journal Volume: 146; Journal Issue: 6; Journal ID: ISSN 0021-9606
American Institute of Physics (AIP)
Research Org:
Arizona State Univ., Tempe, AZ (United States); Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Science Foundation (NSF)
Country of Publication:
United States
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1340505; OSTI ID: 1361771