Matrix t2*K(2) in Subspace 46 with Dimension 3

(K(2) is the second-order Grosse operator)

-3*t*U (3*(1 - I*Sqrt[3])*t*U)/(2*Sqrt[2]) 0
(3*(1 + I*Sqrt[3])*t*U)/(2*Sqrt[2]) (-9*t*U)/2 (-I/4)*(-3*I + Sqrt[3])*U^2
0 (I/4)*(3*I + Sqrt[3])*U^2 (-3*t*U)/2