semi_empirical_mass Class Reference

Semi-empirical mass formula. More...

#include <nuclear_mass.h>

Inheritance diagram for semi_empirical_mass:

nuclear_mass_fit nuclear_mass_cont nuclear_mass nuclear_mass_info

Detailed Description

Semi-empirical mass formula.

A simple semi-empirical mass formula of the form

\[ E/A = B + S_s \frac{1}{A^{1/3}}+E_c \frac{Z^2}{A^{4/3}} + S_v \left(1-\frac{2Z}{A}\right)^2+E_{\mathrm{pair}}(Z,N) \]

where

\[ E_{\mathrm{pair}}(Z,N) = \frac{E_{\mathrm{pair}}}{A^{3/2}} \times \left\{ \begin{array}{rl} -1 & \mathrm{N~and~Z~even} \\ +1 & \mathrm{N~and~Z~odd} \\ 0 & \mathrm{otherwise} \end{array} \right. \]

Note:
The default parameters are arbitrary, and are not determined from a fit.
There is an example of the usage of this class given in Nuclear mass fit example.

Definition at line 491 of file nuclear_mass.h.


Public Member Functions

virtual const char * type ()
 Return the type, "semi_empirical_mass".
virtual double mass_excess_d (double Z, double N)
 Given Z and N, return the mass excess in MeV.
virtual int fit_fun (size_t nv, const ovector_base &x)
 Fix parameters from an array for fitting.
virtual int guess_fun (size_t nv, ovector_base &x)
 Fill array with guess from present values for fitting.

Data Fields

double B
 Binding energy (negative and in MeV, default -16).
double Sv
 Symmetry energy (in MeV, default 23.7).
double Ss
 Surface energy (in MeV, default 18).
double Ec
 Coulomb energy (in MeV, default 0.7).
double Epair
 Pairing energy (MeV, default 13.0).

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

Documentation generated with Doxygen and provided under the GNU Free Documentation License. See License Information for details.

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