Matrix t2*K(2) in Subspace 79 with Dimension 4

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

-3*t*U -(U^2/Sqrt[2]) 4*t^2 (t*U)/Sqrt[2]
-(U^2/Sqrt[2]) (-7*t*U)/2 -((t*U)/Sqrt[2]) -4*t^2
4*t^2 -((t*U)/Sqrt[2]) -7*t*U 0
(t*U)/Sqrt[2] -4*t^2 0 (-15*t*U)/2