This code computes structure factors using the PME approach. Either the electron density structure factor can be computed for X-ray scattering (uses form factors), or the total charge density can be computed (uses input force field charges) to evaluate sum rules
License: GNU General Public License v3.0
Shell 1.71%Fortran 96.52%Perl 1.77%
structure_factor_fft's Introduction
we keep two different branches of this code,
which share common subroutines.
We try to minimize the code files in the
different branches, and keep as much overlap as possbile in
the common subroutines. The reason we have two different
branches is that the data structures get messy when
computing correlation functions such as S(q,t)
1) Sq_Average_FFT:
computes average structure factor, either charge density or number density
structure factor. For charge density, can be split into cation, anion, and
total contribution. For number density, can be split into partial atomic
structure factors. This code returns 3D structure factors, S(qvec), which
may be used for analysis of anisotropic systems, or subsequently averaged
as a function of |qvec| using perl scripts.
2) Sq_Ct_FFT:
In addition to computing averaged structure factors, this branch computes correlation
functions, e.g. S(q,t) for structure factors. In this code we assume isotropic system
so that we don't have correlation functions for all qvecs, and thus we internally average
over qvecs to output S(|qvec|,t)
Both of these branches share code in
"source_shared" directory