Matrix t2*K(2) in Subspace 76 with Dimension 4

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

-2*t*U -4*t^2 (t*U)/Sqrt[2] 0
-4*t^2 -6*t*U U^2/Sqrt[2] (t*U)/Sqrt[2]
(t*U)/Sqrt[2] U^2/Sqrt[2] (-11*t*U)/2 -4*t^2
0 (t*U)/Sqrt[2] -4*t^2 (-3*t*U)/2