Dresden 2011 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 47: Heterogeneous Nucleation and Microstructure Formation (related to SYMF, jointly with MM)
CPP 47.9: Vortrag
Freitag, 18. März 2011, 12:30–12:45, ZEU 160
Curvature Dependence of Surface Free Energy of Liquid Drops and Bubbles — B. J. Block1, S. K. Das2, •M. Oettel1,3, P. Virnau1, and K. Binder1 — 1Institut für Physik, Universität Mainz, Germany — 2Theoretical Sciences Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, India — 3Material- und Prozesssimulation, Universität Bayreuth, Germany
We study the excess free energy due to phase coexistence of fluids
by Monte Carlo simulations using successive umbrella sampling in
finite boxes with periodic boundary
conditions, allowing for stable spherical/cylindrical droplets or flat interface configurations [1]. Both the vapor-liquid phase coexistence of a simple Lennard-Jones fluid and the coexistence between A-rich and B-rich phases of a symmetric binary (AB) Lennard-Jones mixture are
studied.
For the surface tension γ (R) of
droplets/bubbles in the
vapor-liquid case, we find for R →
∞ the leading order (Tolman) correction for droplets has sign opposite to
the case of bubbles, consistent with the Tolman length being independent on the sign of curvature. For the symmetric binary mixture the
expected non-existence of the Tolman length is confirmed. In all
cases and for a range of radii R relevant for nucleation theory,
γ(R) deviates strongly from γ (∞) which can be accounted
for by
a term of order γ
(∞)/γ(R)−1 ∝ R−2.
Comparison with density functional
theory in the vapor-liquid case yields agreement in the overall behavior of γ(R) as well as
in the sign and magnitude of the Tolman length.
B. J. Block, S. K. Das, M. Oettel, P. Virnau, and K. Binder, J. Chem. Phys. 133, 154702 (2010).