36 research outputs found
Nonexistence of classical diamagnetism and nonequilibrium fluctuation theorems for charged particles on a curved surface
We show that the classical Langevin dynamics for a charged particle on a
closed curved surface in a time-independent magnetic field leads to the
canonical distribution in the long time limit. Thus the Bohr-van Leeuwen
theorem holds even for a finite system without any boundary and the average
magnetic moment is zero. This is contrary to the recent claim by Kumar and
Kumar (EPL, {\bf 86} (2009) 17001), obtained from numerical analysis of
Langevin dynamics, that a classical charged particle on the surface of a sphere
in the presence of a magnetic field has a nonzero average diamagnetic moment.
We extend our analysis to a many-particle system on a curved surface and show
that the nonequilibrium fluctuation theorems also hold in this geometry.Comment: 6 pages; typos correcte
Nonequilibrium steady states in contact: Approximate thermodynamic structure and zero-th law for driven lattice gases
We explore driven lattice gases for the existence of an intensive
thermodynamic variable which could determine "equilibration" between two
nonequilibrium steady-state systems kept in weak contact. In simulations, we
find that these systems satisfy surprisingly simple thermodynamic laws, such as
the zero-th law and the fluctuation-response relation between the
particle-number fluctuation and the corresponding susceptibility remarkably
well. However at higher densities, small but observable deviations from these
laws occur due to nontrivial contact dynamics and the presence of long-range
spatial correlations.Comment: Revised, 4 pages, 5 figure