- #1
Auteng
- 20
- 1
Dear friends
How can i calculate RDF(radial distribution function)?
Thanks
How can i calculate RDF(radial distribution function)?
Thanks
Purely statistics. Instead of a cube, take a sphere and use a higher number of particles. You should realize that 8 particles in a bin is ##\pm\sqrt8## ! If you want a noise band of 1%, make sure that even in the higher ##r## bins there are at least 10000 particles per bin !Auteng said:Why it is not smooth
From where you nicked the picture .The RDF is usually determined by calculating the distance between all particle pairs and binning them into a histogram. The histogram is then normalized with respect to an ideal gas, where particle histograms are completely uncorrelated. For three dimensions, this normalization is the number density of the system multiplied by the volume of the spherical shell, which mathematically can be expressed as ##{\displaystyle g(r)_{I}=4\pi r^{2}\rho dr}##, where ##{\displaystyle \rho }## is the number density.
Not to be confused with the Dirac delta function, ...
Can't read it. What is the dimension of particleateachbin ?Auteng said:I write the RDF formula:
$$g(r)=\frac{\frac{particle at each bin} {4 \pi r^2}} {\frac{total number of atoms} {V total}}$$
But i don't understand why the following link two times divided it by N. I think we should divide by N one time according to the formula that i have wrote...
http://www.physics.emory.edu/faculty/weeks//idl/gofr2.html
And remember: that is ##g(r)dr##, not ##g(r)## -- check dimensionsAuteng said:particleateachbin=particle at each bin(particles between r , r+dr)
totalnumberofatoms=total number of atoms(N)
For three dimensions, this normalization is the number density of the system multiplied by the volume of the spherical shell, which mathematically can be expressed as ##{\displaystyle g(r)_{I}=4\pi r^{2}\rho dr}##, where ##{\displaystyle \rho }## is the number density.
(same as post #5). Do you expect a difference ?Auteng said:I think i should take average over all of particles...??!
Is that a question ? After all, it's your calculation: you should know that better than anyone elseWhat i write is for one particle...?!
RDF, or Radial Distribution Function, is a measure of the spatial distribution of particles in a system. It is commonly used in the field of molecular dynamics to analyze the structure of a system.
RDF is calculated by dividing the number of particles within a certain distance from a reference particle by the expected number of particles in that distance interval. This calculation is repeated for various distance intervals to obtain a complete RDF curve.
The inputs required for calculating RDF include the coordinates of the particles in the system and the box dimensions. These can be obtained from a molecular dynamics simulation or experimental data.
The RDF curve represents the probability of finding a particle at a certain distance from a reference particle. It provides information on the structure and interactions within a system.
RDF is limited by the assumption of a homogeneous system and the need for a large number of particles to obtain accurate results. It also does not provide information on the dynamics of the system, only the spatial distribution.