Matrix t2*K(2) in Subspace 17 with Dimension 4

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

(-9*t*U)/2 -(U^2/Sqrt[2]) 0 U^2
-(U^2/Sqrt[2]) -3*t*U -(Sqrt[3/2]*t*U) 0
0 -(Sqrt[3/2]*t*U) (-3*t*U)/2 Sqrt[3]*t*U
U^2 0 Sqrt[3]*t*U -3*t*U