  It is noted that the simple interaction in isospin variables $a (1/4 -
t(i)\cdot t(j))$, in a single $j$ shell calculation, can also be written with
angular momentum variables. For the configuration $(j^2) J_A$ for even $J_A$
the isospin is one; for odd $J_A$ it is zero. Hence the above interaction can
also be written as $a (1 - (-1)^{J_A})/2$. For the I=0 state of an even-even Ti
isotope with $n$ neutrons, the hamiltonian matrix element of this interaction
is $\bra [J'J']_0 |H| [JJ]_0\ket/a = (n+1) \delta_{JJ'}
  - (n+1) (j^n Jj|\} j^{n+1} j)
  (j^n J'j|\} j^{n+1} j)$. The eigenvalues of this interaction can be found by
using the isospin form of the interaction. They are $(n+1)a$ for $T = |N-Z|/2$
and zero for $T = |N-Z|/2 + 2$. One can apply this to some extent to obtain the
number of pairs of nucleons with given total angular momentum $J_A$ in a given
Ti isotope.
