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Rubber band

  1. Jan 8, 2009 #1


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    In the text, there is a rubber band model for 1D chain of N links. Assume each link of the rubber band is align horizontally either to the right or to the left. In the text, define [tex]N_+[/tex] as the number of links directed to the right and [tex]N_-[/tex] represents the number of links directed to the left. I think the total configuration of the system should be

    [tex]\Omega = \frac{N!}{N_+!N_-!}[/tex]

    but it is

    [tex]\Omega = \frac{2N!}{N_+!N_-!}[/tex]

    I wonder where is the "2" come from?
  2. jcsd
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