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In statistical physics, the BBGKY hierarchy (Bogoliubov–Born–Green–Kirkwood–Yvon hierarchy, sometimes called Bogoliubov hierarchy) is a set of equations describing the dynamics of a system of a large number of interacting particles. The equation for an ''s''-particle distribution function (probability density function) in the BBGKY hierarchy includes the (''s'' + 1)-particle distribution function thus forming a coupled chain of equations. This formal theoretic result is named after Bogoliubov, Born, Green, Kirkwood, and Yvon. ==Formulation== The evolution of an ''N''-particle system is given by the Liouville equation for the probability density function in ''6N'' dimensional phase space (3 space and 3 momentum coordinates per particle) : By integration over part of the variables, the Liouville equation can be transformed into a chain of equations where the first equation connects the evolution of one-particle probability density function with the two-particle probability density function, second equation connects the two-particle probability density function with the three-particle probability density function, and generally the ''s''-th equation connects the ''s''-particle probability density function with the ''(s+1)''-particle probability density function: : Here are the coordinates and momentum for ''i''th particle, is the external field potential, and is the pair potential for interaction between particles. The equation above for ''s''-particle distribution function is obtained by integration of the Liouville equation over the variables . 抄文引用元・出典: フリー百科事典『 ウィキペディア(Wikipedia)』 ■ウィキペディアで「BBGKY hierarchy」の詳細全文を読む スポンサード リンク
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