Matrix t2*K(2) in Subspace 55 with Dimension 8

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

-6*t*U -(Sqrt[3]*(4*t^2 + U^2))/2 0 0 0 2*Sqrt[3]*t^2 -(Sqrt[3]*t*U)/2 0
-(Sqrt[3]*(4*t^2 + U^2))/2 (-5*t*U)/2 (Sqrt[3]*t*U)/2 3*t*U 0 (3*t*U)/2 4*t^2 t^2*(2 - U^2/(2*t^2))
0 (Sqrt[3]*t*U)/2 (-9*t*U)/2 0 0 -(Sqrt[3]*t*U)/2 (Sqrt[3]*U^2)/2 0
0 3*t*U 0 -3*t*U 0 0 0 0
0 0 0 0 -6*t*U 0 -3*t*U 0
2*Sqrt[3]*t^2 (3*t*U)/2 -(Sqrt[3]*t*U)/2 0 0 (-7*t*U)/2 t^2*(-4 - U^2/(2*t^2)) -2*t^2
-(Sqrt[3]*t*U)/2 4*t^2 (Sqrt[3]*U^2)/2 0 -3*t*U t^2*(-4 - U^2/(2*t^2)) (-13*t*U)/2 (3*t*U)/2
0 t^2*(2 - U^2/(2*t^2)) 0 0 0 -2*t^2 (3*t*U)/2 -4*t*U