  A previous paper of the author developed a general method for producing
explicit central elements of quantized Lie algebras using Lusztig's inner
product. This method had previously been applied for the type $C_2$, $D_3$ and
$D_4$ Lie algebras. The current paper repeats the calculation for the type
$B_2$ Lie algebra, which is actually isomorphic to the $C_2$ Lie algebra. The
explicit expression for the corresponding quantum Hamiltonian is computed.
