NONEXTENSIVE MICROSCOPIC BEHAVIOR OF LONG-RANGE INTERACTING PARTICLES IN PERIODIC MEDIA

2000 ◽  
Vol 11 (03) ◽  
pp. 629-634 ◽  
Author(s):  
SERGIO CURILEF

This work presents a possible way to study the long-range interacting particles in finite-infinite (mesoscopic-macroscopic) systems with periodic boundary conditions. A symmetric lattice and their contributions over all space are used in the problem. In the present model, we assume that at long distances, the two-body attractive potential decays as a 1/rα law. We verified that the potential in any particle converges (diverges) when the interactions are short(long)-ranged. On the other hand, forces in any particle converge rapidly in all cases. However, we adopt a nonextensive scaling and we guarantee that the potential converges anywhere.

1996 ◽  
Vol 07 (06) ◽  
pp. 873-881 ◽  
Author(s):  
NIELS GRØNBECH-JENSEN

We present a set of expressions for evaluating energies and forces between particles interacting logarithmically in a finite two-dimensional system with periodic boundary conditions. The formalism can be used for fast and accurate, dynamical or Monte Carlo, simulations of interacting line charges or interactions between point and line charges. The expressions are shown to converge to usual computer accuracy (~10–16) by adding only few terms in a single sum of standard trigonometric functions.


Equations for the calculation of the subsonic flow of an inviscid fluid in channels with boundary conditions which are periodic in distance along the channel (for example flow in a closed circuit such as an annulus) are derived. Three types of boundary conditions are considered, namely, ( i ) shape of the walls given (‘direct’ problem), ( ii ) pressures or velocities on the walls given (‘indirect’ problem), and ( iii ) pressures on one wall and the shape of the other wall given (‘mixed’ problem). The theory, which is shown to have numerous aero-dynamic applications, is illustrated by several examples.


Numerical methods are used to study the 4, 6-cell exchange process in the Taylor vortex problem, with particular reference to the homotopy devised by Schaeffer. The homotopy describes a transformation between two models, one incorporating periodic boundary conditions and so referring to flows in an infinite annulus, the other with realistic boundary conditions. Our calculations indicate that the former model is more complicated than previously suspected and lead to a better under­standing of the consequences of Schaeffer’s device.


1996 ◽  
Vol 11 (16) ◽  
pp. 2871-2886 ◽  
Author(s):  
C.G. BENEVENTANO ◽  
E.M. SANTANGELO

We study the connection between ζ- and cutoff-regularized Casimir energies for scalar fields. We show that, in general, both regularization schemes lead to divergent contributions, and to minimal finite parts which do not coincide. We determine the relationships among the various coefficients appearing in one approach and the other. We discuss the agreement with our predictions in the case of scalar fields in d-dimensional boxes under periodic boundary conditions. Finally, we apply our results to massless scalar fields in balls, an example where ambiguities remain under the physical prescriptions usually imposed to extract a finite result.


Author(s):  
Peter A. Banks ◽  
Luke Burgess ◽  
Michael T Ruggiero

Terahertz vibrational spectroscopy has emerged as a powerful spectroscopic technique, providing valuable information regarding long-range interactions - and associated collective dynamics - occurring in solids. However, the terahertz sciences are...


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