%APenrod, Katheryn%APenrod, Katheryn [Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, USA]%ABurgess, Maximiliano%ABurgess, Maximiliano [Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA]%AAkbarian, Dooman%AAkbarian, Dooman [Department of Mechanical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA]%ADabo, Ismaila%ADabo, Ismaila [Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA]%AWoodward, W.%AWoodward, W. [Analytical Science, The Dow Chemical Company, Midland, Michigan 48667, USA]%Avan Duin, Adri%Avan Duin, Adri [Department of Mechanical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA]%BJournal Name: The Journal of Chemical Physics; Journal Volume: 155; Journal Issue: 21; Related Information: CHORUS Timestamp: 2023-06-26 11:21:50 %D2021%IAmerican Institute of Physics %JJournal Name: The Journal of Chemical Physics; Journal Volume: 155; Journal Issue: 21; Related Information: CHORUS Timestamp: 2023-06-26 11:21:50 %K %MOSTI ID: 10391335 %PMedium: X %TUsing C-DFT to develop an e-ReaxFF force field for acetophenone radical anion %X

Increased electricity usage over the past several decades has accelerated the need for efficient high-voltage power transmission with reliable insulating materials. Cross-linked polyethylene (XLPE) prepared via dicumyl peroxide (DCP) cross-linking has emerged as the insulator of choice for modern power cables. Although DCP cross-linking generates the desired XLPE product in high yield, other by-products are also produced. One such by-product, acetophenone, is particularly intriguing due to its aromaticity and positive electron affinity. In this work, constrained density functional theory (C-DFT) was utilized to develop an e-ReaxFF force field suitable for describing the acetophenone radical anion. Initial parameters were taken from the 2021 Akbarian e-ReaxFF force field, which was developed to describe XLPE chemistry. Then, C-DFT geometry optimizations were performed wherein an excess electron was constrained to each atom of acetophenone. The resulting C-DFT energy values for the various electronic positions were added to the e-ReaxFF training set. Next, an analogous set of structures was energy-minimized using e-ReaxFF, and equilibrium mixture compositions for the two methods were compared at multiple temperatures. Iterative fitting against C-DFT energy data was performed until satisfactory agreement was achieved. To test force field performance, molecular dynamics simulations were performed in e-ReaxFF and the resulting electronic distributions were qualitatively compared to unconstrained-DFT spin density data. By expanding our e-ReaxFF force field for XLPE, namely, adding the capability to describe acetophenone and its interactions with an excess electron, we move one step closer to a comprehensive molecular understanding of XLPE chemistry in a high-voltage power cable.

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