Addition of Angular Momenta

Vector additions of 2, 3 and 4 angular momenta have been discussed in this chaper. Properties, orthonormality relations, etc of corresponding coefficients (Clebsch-Gordan coefficient, Racah coefficient or 6j symbol, and 9j symbol respectively) have been presented. Interrelations among these coefficients have also been discussed. For matrix of Clebsch-Gordan coefficients, rows and columns are so arranged that the matrix has block-diagonal structure. Recurrence relations and orthonormality are used to calculate the coefficients. LS and jj coupling schemes are also discussed.