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Cluster pair correlation function of simple fluids: energetic connectivity criteria
Luis A Pugnaloni1, Guillermo J Zarragoicoechea, Fernando Vericat
1Instituto de Física de Líquidos y Sistemas Biológicos (IFLYSIB), UNLP-CONICET, cc. 565, 1900 La Plata, Argentina. luis@iflysib.unlp.edu.ar
Abstract:
We consider the clustering of Lennard-Jones particles by using an energetic connectivity criterion proposed long ago by Hill [J. Chem. Phys. 32, 617 (1955)] for the bond between pairs of particles. The criterion establishes that two particles are bonded (directly connected) if their relative kinetic energy is less than minus their relative potential energy. Thus, in general, it depends on the direction as well as on the magnitude of the velocities and positions of the particles. An integral equation for the pair connectedness function, proposed by two of the authors [Phys. Rev. E 61, R6067 (2000)], is solved for this criterion and the results are compared with those obtained from molecular dynamics simulations and from a connectedness Percus-Yevick-type integral equation for a velocity-averaged version of Hill's energetic criterion.
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