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

-2*h + U	(I/12)*(13*I + Sqrt[3])*t	((3*I + Sqrt[3])*t)/2	0	0	((I + Sqrt[3])*t)/2	0	0	0	((I/3)*(I + Sqrt[3])*t)/Sqrt[2]	0	-((-3*I + Sqrt[3])*t)/4
(-I/12)*(-13*I + Sqrt[3])*t	-2*h + U	0	((-9*I + 5*Sqrt[3])*t)/6	((-4*I)*t)/Sqrt[3]	0	0	0	(Sqrt[2]*(1 + I*Sqrt[3])*t)/3	0	((3*I + Sqrt[3])*t)/12	0
((-3*I + Sqrt[3])*t)/2	0	-2*(h - U)	((3 + I*Sqrt[3])*t)/4	0	0	0	-((-3*I + Sqrt[3])*t)/4	0	0	((3 - I*Sqrt[3])*t)/2	0
0	((9*I + 5*Sqrt[3])*t)/6	((3 - I*Sqrt[3])*t)/4	-2*(h - U)	0	t	-((3*I + Sqrt[3])*t)/4	0	0	2*Sqrt[2/3]*t	0	(I/2)*(I + Sqrt[3])*t
0	((4*I)*t)/Sqrt[3]	0	0	-2*h	0	0	0	0	(3/Sqrt[2] + I/Sqrt[6])*t	0	0
((-I + Sqrt[3])*t)/2	0	0	t	0	-2*h + U	0	-(Sqrt[3]*t)	-(((-I + Sqrt[3])*t)/Sqrt[2])	0	((3 - I*Sqrt[3])*t)/2	0
0	0	0	-((-3*I + Sqrt[3])*t)/4	0	0	-2*(h - U)	(t + (3*I)*Sqrt[3]*t)/4	0	0	-(Sqrt[3]*t)	0
0	0	-((3*I + Sqrt[3])*t)/4	0	0	-(Sqrt[3]*t)	(t - (3*I)*Sqrt[3]*t)/4	-2*(h - U)	0	0	0	0
0	(Sqrt[2]*(1 - I*Sqrt[3])*t)/3	0	0	0	-(((I + Sqrt[3])*t)/Sqrt[2])	0	0	-2*h + U	(I/6)*(7*I + Sqrt[3])*t	0	0
((-I/3)*(-I + Sqrt[3])*t)/Sqrt[2]	0	0	2*Sqrt[2/3]*t	(3/Sqrt[2] - I/Sqrt[6])*t	0	0	0	(-I/6)*(-7*I + Sqrt[3])*t	-2*h + U	((3*I + Sqrt[3])*t)/(3*Sqrt[2])	0
0	((-3*I + Sqrt[3])*t)/12	((3 + I*Sqrt[3])*t)/2	0	0	((3 + I*Sqrt[3])*t)/2	-(Sqrt[3]*t)	0	0	((-3*I + Sqrt[3])*t)/(3*Sqrt[2])	-2*h + U	(I/4)*(5*I + Sqrt[3])*t
-((3*I + Sqrt[3])*t)/4	0	0	(-I/2)*(-I + Sqrt[3])*t	0	0	0	0	0	0	(-I/4)*(-5*I + Sqrt[3])*t	-2*h + U