H is the Hamiltonian. Here we set µ=0. For grand-canonical calculations add -6µ to the main diagonal.

-2*h + U	t	Sqrt[2]*t	0	0	0	0	0
t	-2*h + U	0	t	0	0	2*t	-t
Sqrt[2]*t	0	-2*(h - U)	0	0	0	-(Sqrt[2]*t)	Sqrt[2]*t
0	t	0	-2*(h - U)	-2*t	-(Sqrt[2]*t)	0	0
0	0	0	-2*t	-2*(h - U)	0	0	2*t
0	0	0	-(Sqrt[2]*t)	0	-2*(h - U)	-(Sqrt[2]*t)	0
0	2*t	-(Sqrt[2]*t)	0	0	-(Sqrt[2]*t)	-2*h + U	0
0	-t	Sqrt[2]*t	0	2*t	0	0	-2*h + U