Benchmarking Semiempirical Methods to Compute Electrochemical Formal Potentials

Rebecca L.M. Gieseking, Mark A Ratner, George C Schatz

Research output: Contribution to journalArticle

Abstract

Computational methods to predict and tune electrochemical redox potentials are important for the development of energy technologies. Here, we benchmark several semiempirical models to compute reduction potentials of organic molecules, comparing approaches based on (1) energy differences between the S0 and one-electron-reduced D0 states of the isolated molecules and (2) an orbital energy shift approach based on tuning the charge-Transfer triplet energy of the Ag20-molecule complex; the second model enables explicit modeling of electrode-molecule interactions. For molecules in solution, the two models yield nearly identical results. Both PM7 and PM6 predict formal potentials with only a slight loss of accuracy compared to standard density functional theory models, and the results are robust across several choices of geometries and implicit solvent models. PM6 and PM7 show dramatically improved accuracy over older semiempirical Hamiltonians (MNDO, AM1, PM3, and INDO/S). However, our recently developed INDO parameters model the electronic properties of our Ag20 model electrode much more accurately than does PM7. These results demonstrate the need for further development of semiempirical models to accurately model molecules on surfaces.

Original languageEnglish
Pages (from-to)6809-6818
Number of pages10
JournalJournal of Physical Chemistry A
Volume122
Issue number33
DOIs
Publication statusPublished - Aug 23 2018

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Benchmarking
Molecules
molecules
energy technology
Hamiltonians
Electrodes
electrodes
Computational methods
Electronic properties
Density functional theory
energy
Charge transfer
Tuning
tuning
charge transfer
density functional theory
orbitals
Geometry
Electrons
shift

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

Cite this

Benchmarking Semiempirical Methods to Compute Electrochemical Formal Potentials. / Gieseking, Rebecca L.M.; Ratner, Mark A; Schatz, George C.

In: Journal of Physical Chemistry A, Vol. 122, No. 33, 23.08.2018, p. 6809-6818.

Research output: Contribution to journalArticle

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