How can I get "STRUCTURE FACTOR" from MD simulation?

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maryam · #1 Post by **maryam** » Mon Apr 12, 2010 12:24 pm

Dear friends,

Is there any output file which contains "STRUCTURE FACTOR", as PCDAT file that it contains averaged pair correlation function?

I have written a Fortran code for calculation of structure factor by using CONTCAR as input, but my results are different from what is in the literature. In spite of I have checked my program many times!

I'm very thankful for any idea.

#2 Post by **admin** » Tue Apr 13, 2010 3:22 pm

the structure factor can be obtained by Fourier transformation of the pair correlation function (as written in PCDAT) (please see Kresse and Hafner, PRB49, 14251 (1994)

maryam · #3 Post by **maryam** » Wed Apr 14, 2010 7:41 am

Thank you very much, administrator!

I think Kresse and Hafner, PRB49, 14251 (1994), have used another method, since they have expressed that "Calculation of S(Q) [structure factor] by Fourier transforming of g(r) [pair correlation function] can lead to results that are seriously affected by truncation errors." My written code for calculation of structure factor is based on their mentioned equation, (29) over all atom pairs. But, I couldn't get good results.
Regarding to Eq. (29), the structure factor should be non-zero for Q=0 while its value is zero in its shown figure! I don't know where is my mistake?

Thank you for any other idea!