PROFASI
Version 1.5
|
Circular normal potential well. More...
#include <RestraintFunction.hh>
Public Member Functions | |
int | set_pars (prf_xml::XML_Node *pars) |
Set parameters for circular normal potential. | |
double | operator() (double x) |
Evaluate the function for a given value of the coordinate. | |
double | estimate_max (double scale_large) |
Estimate a maximum based on some "large" scale. | |
![]() | |
RestraintFunction () | |
Default constructor. | |
virtual double | estimate_min () |
Estimate a minimum. | |
This is an adaptation of the circular normal or von Mises distribution for use as a potential well in angle space. The von Mises distribution is given by
where
is the modified Bessel function. The parameter
kappa
roughly corresponds to the inverse of the square of the width of the distribution. The angle in question does not appear in the denominator. It is therefore convenient to modify the function to :
This way of writing the function makes sure that the value is 0 when the the angle takes its mean value, and N when it is not. The user can choose the location (mu), width ( roughly inverse square-root of kappa ) and the depth (N) of the potential well.
|
virtual |
The XML node passed should be a parameters
node with up to 3 child fields called kappa
, mean
and weight
in arbitrary order. Example:
<parameters> <mean>1.1342</mean> <kappa>8</kappa> <weight>10</weight> <parameters>
Reimplemented from prf::RestraintFunction.