How do I calculate the pair distribution function, g(r), if I know a list of particle centres?

Question

Sudharsan Srinivasan 2021-1-20

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https://ww2.mathworks.cn/matlabcentral/answers/722419-how-do-i-calculate-the-pair-distribution-function-g-r-if-i-know-a-list-of-particle-centres

评论： Hisay Lama 2023-7-6

I have a list of particle centre of mass in x, y, and z directions. I want to calculate the pair distribution function, g(r) that basically tells about the probability of finding a particle next to the reference particle. I followed the procedure given in this link How to calculate the pair correlation function g(r) (emory.edu), but didn't get the result as expected. This is what I tried.

count = 0;

for i = 1:np % np is the number of particles

for j = (i+1):np

dist = sqrt((x(i)-x(j))^2 + (y(i)-y(j))^2 + (z(i)-z(j))^2) % x, y, and z are the particle centre of mass

for r = 1:del_r:50 % for now i used del_r=1

volume(r) = 4*pi*r^2*del_r;

if (dist < r) && (dist < (r + del_r))

count = count + 1; % the problem is to count the number of particles that satisfy this if condition.

tot_count(r) = count/np;

end

cnt_ovr_vol = tot_count./volume;

num_den = np/(nx*ny*nz); %nx = ny = nz = 100;