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26 //
27 // -------------------------------------------------------------------
28 // GEANT4 Class file
29 //
30 //
31 // File name: G4Clebsch
32 //
33 // Author: Maria Grazia Pia (MariaGrazia.Pia@genova.infn.it)
34 //
35 // Creation date: 15 April 1999
36 //
37 // Modifications: February 2015, Jason Detwiler (jasondet@gmail.com)
38 // - Update variable names to clarify that twice
39 // the spin value is being used.
40 // - Add function to obtain raw CG coeffients
41 // - Speed up Wigner 3j evaluation by removing
42 // reallocation of vector<double>'s on every call
43 // - Use G4Pow instead of internal logs variable
44 // - Add functions for Wigner 6j and 9j symbols,
45 // Racah coefficients, and d-Matrices
46 // - Make functions statically available
47 // - Eliminate unnecessary constructors, destructors,
48 // operators (class has no members, so default versions
49 // are adequate)
50 // 11.06.2015 V.Ivanchenko adopted for Geant4 source
51 //
52 // Clebsch-Gordan coefficient and related algebra
53 //
54 // -------------------------------------------------------------------
55
56 #ifndef G4CLEBSCH_HH
57 #define G4CLEBSCH_HH
58
59 #include "globals.hh"
60 #include <vector>
61
62 class G4Clebsch
63 {
64 public:
65 // Calculates the standard Clebsch-Gordan coefficient with Condon-Shortley
66 // phase convention.
67 static
68 G4double ClebschGordanCoeff(G4int twoJ1, G4int twoM1,
69 G4int twoJ2, G4int twoM2,
70 G4int twoJ);
71
72 // Calculates the square of the corresponding Clebsch-Gordan coefficient
73 static
74 G4double ClebschGordan(G4int twoJ1, G4int twoM1,
75 G4int twoJ2, G4int twoM2,
76 G4int twoJ);
77
78 static
79 std::vector<G4double> GenerateIso3(G4int twoJ1, G4int twoM1,
80 G4int twoJ2, G4int twoM2,
81 G4int twoJOut1, G4int twoJOut2);
82
83 static
84 G4double Weight(G4int twoJ1, G4int twoM1,
85 G4int twoJ2, G4int twoM2,
86 G4int twoJOut1, G4int twoJOut2);
87
88 // Deprecated G4double version of Wigner3J that assumes user sent in half-int
89 // values. Use G4int version instead, which guarantees validity of arguments.
90 static
91 G4double Wigner3J(G4double j1, G4double j2, G4double j3,
92 G4double m1, G4double m2, G4double m3);
93
94 // Wigner's 3J symbols (CG-coeffs with a different phase and normalization)
95 static G4double Wigner3J(G4int twoJ1, G4int twoM1,
96 G4int twoJ2, G4int twoM2,
97 G4int twoJ3);
98 static G4double Wigner3J(G4int twoJ1, G4int twoM1,
99 G4int twoJ2, G4int twoM2,
100 G4int twoJ3, G4int twoM3);
101
102 // Calculates the normalized Clebsch-Gordan coefficient, that is the prob
103 // of isospin decomposition of (J,m) into J1, J2, m1, m2
104 static
105 G4double NormalizedClebschGordan(G4int twoJ, G4int twom,
106 G4int twoJ1, G4int twoJ2,
107 G4int twom1, G4int twom2);
108
109 // Triangle coefficient appearing in explicit calculation of CG-coeffs
110 static G4double TriangleCoeff(G4int twoA, G4int twoB, G4int twoC);
111
112 // Wigner's 6J symbols (generalization of CG's for coupling of 3 angular momenta).
113 static G4double Wigner6J(G4int twoJ1, G4int twoJ2, G4int twoJ3,
114 G4int twoJ4, G4int twoJ5, G4int twoJ6);
115
116 // Racah's W Coeffs (6J's with a different phase and normalization)
117 static G4double RacahWCoeff(G4int twoJ1, G4int twoJ2,
118 G4int twoJ, G4int twoJ3,
119 G4int twoJ12, G4int twoJ23);
120
121 // Wigner's 9J symbols (generalization of CG's for coupling of 4 angular momenta).
122 static G4double Wigner9J(G4int twoJ1, G4int twoJ2, G4int twoJ3,
123 G4int twoJ4, G4int twoJ5, G4int twoJ6,
124 G4int twoJ7, G4int twoJ8, G4int twoJ9);
125
126 // Wigner's little-d matrix
127 static G4double WignerLittleD(G4int twoJ, G4int twoM, G4int twoN,
128 G4double cosTheta);
129 };
130
131 #endif
132
133