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SUMMARY:A coarse-grained perspective on water's dielectric response at int
 erfaces - Georg Menzl\, Lawrence Berkeley National Laboratory
DTSTART:20211011T153000Z
DTEND:20211011T160000Z
UID:TALK162295@talks.cam.ac.uk
CONTACT:Dr Christoph Schran
DESCRIPTION:The local dielectric permittivity changes abruptly at the wate
 r–air interface\, from ϵ ≈ 80 in the bulk liquid to ϵ ≈ 1 in the v
 apor. Previous work has suggested that ϵ(z) should be viewed as a highly 
 structured function of distance z from the surface\, changing sign and exh
 ibiting multiple singularities as z approaches zero. Here we present theor
 y and computer simulations that largely reconcile the spatially coarse-gra
 ined dielectric response observed at interfaces with bulk material propert
 ies. We develop a novel dielectric continuum theory expression that takes 
 the boundary\nconditions at the interface into account appropriately and p
 redicts how dipole fluctuations in probe volumes are modestly suppressed n
 ear the interface. This simple\nmodel accurately predicts relative correla
 tions between net polarizations down to probe volumes containing only a fe
 w molecules on average\, both in bulk and at interfaces. We find that dipo
 le probability distributions from numerical simulations rapidly\napproach 
 a large deviation form whose non-Gaussian features are chiefly responsible
  for the finite size effects observed in the linear dielectric response. T
 he success of our simple model in conjunction with the similarities betwee
 n bulk and interfacial rate functions suggests that water's dielectric per
 mittivity retains its bulk value essentially up to the water–air interfa
 ce.
LOCATION:https://zoom.us/j/92447982065?pwd=RkhaYkM5VTZPZ3pYSHptUXlRSkppQT0
 9
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