Difference between revisions of "Pair Distribution Function"

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(New page: For a system with N particles, the ''configurational distribution function'', <math>F_N(r_1,...,r_N)</math>, of the system appears in the nature of a probability density and satisfies the ...)
 
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For a system with N particles, the ''configurational distribution function'', <math>F_N(r_1,...,r_N)</math>, of the system appears in the nature of a probability density and satisfies the normalizaiton condition  
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For a system with N particles, the ''configurational distribution function'', <math>F_N(r_1,...,r_N)</math>, of the system appears in the nature of a probability density and satisfies the normalizaiton condition
<math>\int F_N(r_1,...,r_N) d^3r_1 ... d^3r_N =1</math>
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<math>\int F_N(r_1,...,r_N) d^3r_1 ... d^3r_N =1</math>.
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Integrating <math>F_N(r_1,...,r_N)</math> over the coordinates <math>r_2</math>, ..., <math>r_N</math> and multiplying the result by ''N'', a single particle distribution function can be obtained
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<math>F_1(r_1)= N \int F_N(r_1,...,r_N) d^3r_2 ... d^3r_N =n(r_1)</math>. 
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The function <math>F_1(r_1)</math> represents the particle density at the point <math>r_1</math>.
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The two-particle distribution function is now defined as
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<math>F_2(r_1,r_2)= N (N-1) \int F_N(r_1,...,r_N) d^3r_3 ... d^3r_N =n^2 g(r)</math>,
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where <math>r=r_2-r_1</math>. The above equation defines the ''pair distribution funciton'' <math>g(r)</math> of the system. The product <math>g(r) d^3r</math> determines the probability of finding a particle in the volume element <math>d^3r</math> around the point <math>r</math> when there has been a particle at the point <math>r=0</math>

Revision as of 03:42, 25 October 2009

For a system with N particles, the configurational distribution function, <math>F_N(r_1,...,r_N)</math>, of the system appears in the nature of a probability density and satisfies the normalizaiton condition

<math>\int F_N(r_1,...,r_N) d^3r_1 ... d^3r_N =1</math>.

Integrating <math>F_N(r_1,...,r_N)</math> over the coordinates <math>r_2</math>, ..., <math>r_N</math> and multiplying the result by N, a single particle distribution function can be obtained

<math>F_1(r_1)= N \int F_N(r_1,...,r_N) d^3r_2 ... d^3r_N =n(r_1)</math>.  

The function <math>F_1(r_1)</math> represents the particle density at the point <math>r_1</math>. The two-particle distribution function is now defined as

<math>F_2(r_1,r_2)= N (N-1) \int F_N(r_1,...,r_N) d^3r_3 ... d^3r_N =n^2 g(r)</math>,

where <math>r=r_2-r_1</math>. The above equation defines the pair distribution funciton <math>g(r)</math> of the system. The product <math>g(r) d^3r</math> determines the probability of finding a particle in the volume element <math>d^3r</math> around the point <math>r</math> when there has been a particle at the point <math>r=0</math>