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

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