Experimental and Modeling Studies of Local and Nanoscale para-Cresol Behavior: A Comparison of Classical Force Fields

Katie S.C. Morton, Alin M. Elena, Jeff Armstrong, Alexander O'Malley

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Abstract

The dynamics of bulk liquid para-cresol from 340-390 K was probed using a tandem quasielastic neutron scattering (QENS) and molecular dynamics (MD) approach, due to its relevance as a simple model component of lignin pyrolysis oil. QENS experiments observed both translational jump diffusion and isotropic rotation, with diffusion coefficients ranging from 10.1 to 28.6 × 10-10 m2s-1 and rotational rates from 5.7 to 9.2 × 1010 s-1. The associated activation energies were 22.7 ± 0.6 and 10.1 ± 1.2 kJmol-1 for the two different dynamics. MD simulations applying two different force field models (OPLS3 and OPLS2005) gave values close to the experimental diffusion coefficients and rotational rates obtained upon calculating the incoherent dynamic structure factor from the simulations over the same time scale probed by the QENS spectrometer. The simulations gave resulting jump diffusion coefficients that were slower by factors of 2.0 and 3.8 and rates of rotation that were slower by factors of 1.2 and 1.6. Comparing the two force field sets, the OPLS3 model showed slower rates of dynamics likely due to a higher molecular polarity, leading to greater quantities and strengths of hydrogen bonding.

Original languageEnglish
Pages (from-to)3305-3316
Number of pages12
JournalJournal of Physical Chemistry A
Volume127
Issue number15
Early online date11 Apr 2023
DOIs
Publication statusPublished - 20 Apr 2023

Bibliographical note

Funding Information:
This work was supported by the UK Engineering and Physical Sciences Research Council (EPSRC) grant EP/T518013/1 for the University of Bath as part of a studentship with the STFC. The ISIS neutron and muon source at the STFC Rutherford Appleton Laboratory are thanked for access to neutron beam facilities. The authors thank the STFC facilities for access to computing resources on the SCARF computer cluster. A. J. O’Malley acknowledges Roger and Sue Whorrod for the funding of a Whorrod Fellowship. We also thank A. J. Porter for initial guidance with data processing. The resources and support provided by the UK Catalysis Hub via membership of the UK Catalysis Hub consortium are gratefully acknowledged.

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

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