src/Level1/Wigner.cc
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//           REDUCED WIGNER ROTATION MATRIX ELEMENTS: RANK 2 
// ______________________________________________________________________
REDUCED WIGNER ROTATION MATRIX ELEMENTS: RANK 2
REDUCED WIGNER ROTATION MATRIX ELEMENTS : RANK 2
double d22(int n, double beta )
  {
  double r=0;
    switch (n)
      {
      case -2:
        r = sin(beta*PI/360.0);		
        r = r*r;			
        r = r*r;			
        break;
      case -1:
        r = beta*DEG2RAD;		
        r = 0.5*sin(r)*(cos(r)-1.0);	
        break;				
      case 0:
        r = sin(beta*DEG2RAD);		
        r = sqrt(3.0/8.0)*r*r;		
        break;				
      case 1:
        r = beta*DEG2RAD;		
        r = -0.5*sin(r)*(1.0+cos(r));	
        break;				
      case 2:
        r = cos(beta*PI/360.0);		
        r = r*r;			
        r = r*r;			
        break;
      default:
        Wigner_error(2);
        cout << "2," << n;
        Wigner_fatality(10);
        break;
      }
  return r;
  }
double d22 ( int n , double beta ) { double r = 0 ; switch ( n ) { case -2 : r = sin ( beta * PI / 360.0 ) ; r = r * r ; r = r * r ; break ; case -1 : r = beta * DEG2RAD ; r = 0.5 * sin ( r ) * ( cos ( r ) - 1.0 ) ; break ; case 0 : r = sin ( beta * DEG2RAD ) ; r = sqrt ( 3.0 / 8.0 ) * r * r ; break ; case 1 : r = beta * DEG2RAD ; r = -0.5 * sin ( r ) * ( 1.0 + cos ( r ) ) ; break ; case 2 : r = cos ( beta * PI / 360.0 ) ; r = r * r ; r = r * r ; break ; default : Wigner_error ( 2 ) ; cout << " " << n ; Wigner_fatality ( 10 ) ; break ; } return r ; }
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REDUCED WIGNER ROTATION MATRIX ELEMENTS: RANK 2
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______________________________________________________________________ REDUCED WIGNER ROTATION MATRIX ELEMENTS : RANK 2 ______________________________________________________________________
// Input		n     : momentum index // 			beta  : Euler angle // Output		r     : rank 2, m = 2 reduced Wigner rotation //				matrix element // Note 		      : Euler angle input in degrees //  (2)             4 // d    (beta) = sin (beta/2) //  2,-2 //  (2)          1 // d    (beta) = - sin(beta)[cos(beta)-1] //  2,-1         2 //  (2)         [3]1/2   2 // d   (beta) = |-|   sin (beta) //  2,0         [8] //  (2)           1 // d   (beta) = - - sin(beta)[1+cos(beta)] //  2,1           2 //  (2)            4 // d   (beta) = cos (beta/2) //  2,2