• Dielectric relaxations of molten acetamide: dependence on the model interaction potentials and the effects of system size

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      Molecular dynamics simulation; dielectric properties; molten acetamide. 1. Introduction Amide systems are an interesting class of molecules because of their proximity to the world of proteins and peptides in terms of functional groups.1,2 The existence of the peptide bond (-CO-NH-) in amides which is also the linkage unit in polypeptides and proteins makes amides biologica

    • Abstract

       

      Molecular dynamics simulations of dielectric relaxations (DRs) in neat molten acetamide(CH3CONH2) at ~358 K have been carried out by employing two different versions of the OPLS force fieldparameters, namely, the OPLS-UA (united-atom) and the OPLS-AA (all-atom) model interactions. Threesystems consisting of 250, 500, and 1000 molecules have been studied to examine the impact of system sizeon the simulated dielectric properties. A comparison between our simulation predictions and the experimentalDR data in the MHz-GHz frequency regime reveals that the OPLS-UA interaction parameters betterreproduce the experimental static dielectric constant, whereas the OPLS-AA interaction describes well themeasured DR time constants. Moreover, a weak system size dependence has been observed. A Cole-Cole plotof the simulated and experimental dielectric spectra reveal non-Debye nature of liquid acetamide and corroborateswell with the earlier observation on the collective single-particle reorientational relaxation of liquidacetamide. The simulated single dipole reorientation dynamics also reflects this weak non-Debye nature andreveals its contribution to the collective polarization relaxation. Simulation results obtained here set the rightground for investigating the colossal dielectric constant (~106) of ionic acetamide deep eutectics reportedearlier via DR measurements in the KHz-MHz regime.

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    • Author Affiliations

       

      DHRUBAJYOTI MAJI1 SANDIPA INDRA2 RANJIT BISWAS1

      1. Chemical, Biological and Macromolecular Sciences, S. N. Bose National Centre for Basic Sciences, Block- JD, Sector-III, Salt Lake, Kolkata, West Bengal 700106, India
      2. Department of Chemistry, Indian Institute of Technology Patna, Bihar 801106, India
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