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

U	((-1 - I*Sqrt[3])*t)/Sqrt[2]	0	0
(I*(I + Sqrt[3])*t)/Sqrt[2]	U	(-I/2)*(-I + Sqrt[3])*t	0
0	(I/2)*(I + Sqrt[3])*t	U	((-1 - I*Sqrt[3])*t)/Sqrt[2]
0	0	(I*(I + Sqrt[3])*t)/Sqrt[2]	0