Matrix t2*K(2) in Subspace 7 with Dimension 4

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

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