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

U	t	0	0	0	-(Sqrt[3]*t)	0	Sqrt[3]*t
t	U	0	0	Sqrt[6]*t	0	0	0
0	0	3*U	0	-(Sqrt[2]*t)	0	Sqrt[2]*t	0
0	0	0	2*U	0	0	0	2*t
0	Sqrt[6]*t	-(Sqrt[2]*t)	0	2*U	0	0	Sqrt[2]*t
-(Sqrt[3]*t)	0	0	0	0	2*U	Sqrt[2]*t	0
0	0	Sqrt[2]*t	0	0	Sqrt[2]*t	2*U	0
Sqrt[3]*t	0	0	2*t	Sqrt[2]*t	0	0	U