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Title: Frequency-dependent local field factors in dielectric liquids by a polarizable force field and molecular dynamics simulations

A force field model for calculating local field factors, i.e. the linear response of the local electric field for example at a nucleus in a molecule with respect to an applied electric field, is discussed. It is based on a combined charge-transfer and point-dipole interaction model for the polarizability, and thereby it includes two physically distinct terms for describing electronic polarization: changes in atomic charges arising from transfer of charge between the atoms and atomic induced dipole moments. A time dependence is included both for the atomic charges and the atomic dipole moments and if they are assumed to oscillate with the same frequency as the applied electric field, a model for frequency-dependent properties are obtained. Furthermore, if a life-time of excited states are included, a model for the complex frequency-dependent polariability is obtained including also information about excited states and the absorption spectrum. We thus present a model for the frequency-dependent local field factors through the first molecular excitation energy. It is combined with molecular dynamics simulations of liquids where a large set of configurations are sampled and for which local field factors are calculated. We are normally not interested in the average of the local field factor butmore » rather in configurations where it is as high as possible. In electrical insulation, we would like to avoid high local field factors to reduce the risk for electrical breakdown, whereas for example in surface-enhanced Raman spectroscopy, high local field factors are desired to give dramatically increased intensities.« less
Authors:
; ;  [1]
  1. Department of Chemistry, Norwegian University of Science and Technology (NTNU), Trondheim (Norway)
Publication Date:
OSTI Identifier:
22499127
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1702; Journal Issue: 1; Conference: ICCMSE 2015: International conference of computational methods in sciences and engineering 2015, Athens (Greece), 20-23 Mar 2015; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ABSORPTION SPECTRA; COMPUTERIZED SIMULATION; CONFIGURATION; DIELECTRIC MATERIALS; DIPOLE MOMENTS; DIPOLES; ELECTRIC FIELDS; ELECTRICAL FAULTS; ELECTRICAL INSULATION; EXCITATION; EXCITED STATES; FREQUENCY DEPENDENCE; LIQUIDS; MOLECULAR DYNAMICS METHOD; POLARIZABILITY; POLARIZATION; RAMAN SPECTROSCOPY; TIME DEPENDENCE