Faunus::Scatter::DebyeFormula< Tformfactor, T > Class Template Reference

Calculate scattering intensity, I(q), on a mesh using the Debye formula. More...

#include <scatter.h>

Public Member Functions
	DebyeFormula (T q_min, T q_max, T q_step, T r_cutoff)
	DebyeFormula (T q_min, T q_max, T q_step)
	DebyeFormula (const json &j)
template<class Tpvec >
void	sample (const Tpvec &p, const T weight=1, const T volume=-1)
	Sample I(q) and add to average. More...
auto	getQMeshParameters ()
auto	getIntensity ()

Detailed Description

template<class Tformfactor, std::floating_point T = float>
class Faunus::Scatter::DebyeFormula< Tformfactor, T >

Calculate scattering intensity, I(q), on a mesh using the Debye formula.

It is important to note that distances should be calculated without periodicity and if molecules cross periodic boundaries, these must be made whole before performing the analysis.

The JSON object is scanned for the following keywords:

• qmin minimum q value (1/angstrom)
• qmax maximum q value (1/angstrom)
• dq q mesh spacing (1/angstrom)
• cutoff cutoff distance (angstrom); Experimental!

See also

http://dx.doi.org/10.1016/S0022-2860(96)09302-7

Member Function Documentation

getIntensity()

template<class Tformfactor , std::floating_point T = float>

auto Faunus::Scatter::DebyeFormula< Tformfactor, T >::getIntensity ( )

inline

Returns

a map containing q (key) and average intensity (value)

getQMeshParameters()

template<class Tformfactor , std::floating_point T = float>

auto Faunus::Scatter::DebyeFormula< Tformfactor, T >::getQMeshParameters ( )

inline

Returns

a tuple of min, max, and step parameters of a q-mash

sample()

template<class Tformfactor , std::floating_point T = float>

template<class Tpvec >

void Faunus::Scatter::DebyeFormula< Tformfactor, T >::sample ( const Tpvec &  p, const T  weight = 1, const T  volume = -1  )

inline

Sample I(q) and add to average.

Parameters

p	particle vector
weight	weight of sampled configuration in biased simulations
volume	simulation volume (angstrom cubed) used only for cut-off correction

An isotropic correction is added beyond a given cut-off distance. For physics details see for example

See also

https://debyer.readthedocs.org/en/latest/.

O(N^2) * O(M) complexity where N is the number of particles and M the number of mesh points. The quadratic complexity in N comes from the fact that the radial distribution function has to be computed. The current implementation supports OpenMP parallelization. Roughly half of the execution time is spend on computing sin values, e.g., in sinf_avx2.

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The documentation for this class was generated from the following file:

• src/scatter.h