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

2*h + U	((7 + (5*I)*Sqrt[3])*t)/12	0	t/Sqrt[3]	0	((3*I - 5*Sqrt[3])*t)/(6*Sqrt[2])	-((9*I + 5*Sqrt[3])*t)/(6*Sqrt[2])	0	0	0	0	(I/3)*Sqrt[2]*(I + Sqrt[3])*t	0	0	0	-((-3*I + Sqrt[3])*t)/12
((7 - (5*I)*Sqrt[3])*t)/12	2*h + U	0	0	((3*I + 7*Sqrt[3])*t)/6	0	0	0	0	0	((1 - I*Sqrt[3])*t)/(3*Sqrt[2])	0	(((1 - 3*I)*Sqrt[18 - 6*Sqrt[3]] + (5 + 3*I)*Sqrt[6 - 2*Sqrt[3]])*t)/(2*Sqrt[6]*(-3 + Sqrt[3]))	((-3 - 9*I + (5 - 3*I)*Sqrt[3])*t)/(6*Sqrt[3 + Sqrt[3]])	((3*I + Sqrt[3])*t)/4	0
0	0	2*(h + U)	((I/2)*(5*I + Sqrt[3])*t)/Sqrt[2]	0	0	0	0	((-3*I + Sqrt[3])*t)/(2*Sqrt[2])	0	0	0	0	0	0	Sqrt[2]*(1 - I*Sqrt[3])*t
t/Sqrt[3]	0	((-I/2)*(-5*I + Sqrt[3])*t)/Sqrt[2]	2*(h + U)	((-1 + (3*I)*Sqrt[3])*t)/4	0	0	((3*I + Sqrt[3])*t)/(2*Sqrt[2])	0	-((3*I + Sqrt[3])*t)/4	-(Sqrt[2]*(3*I + Sqrt[3])*t)/3	0	0	0	(I/2)*(3*I + Sqrt[3])*t	0
0	((-3*I + 7*Sqrt[3])*t)/6	0	((-1 - (3*I)*Sqrt[3])*t)/4	2*(h + U)	t/Sqrt[2]	-(t/Sqrt[2])	0	-((-3*I + Sqrt[3])*t)/4	0	0	(Sqrt[2]*(-3*I + Sqrt[3])*t)/3	0	0	0	(t + I*Sqrt[3]*t)/2
-((3*I + 5*Sqrt[3])*t)/(6*Sqrt[2])	0	0	0	t/Sqrt[2]	2*h + U	0	0	0	-(Sqrt[3/2]*t)	(-2*t)/Sqrt[3]	0	0	0	((3 - I*Sqrt[3])*t)/(2*Sqrt[2])	0
((9*I - 5*Sqrt[3])*t)/(6*Sqrt[2])	0	0	0	-(t/Sqrt[2])	0	2*h + U	0	0	Sqrt[3/2]*t	((3*I + Sqrt[3])*t)/3	0	0	0	((-I/2)*(-I + Sqrt[3])*t)/Sqrt[2]	0
0	0	0	((-3*I + Sqrt[3])*t)/(2*Sqrt[2])	0	0	0	2*(h + U)	((-I/2)*(-3*I + Sqrt[3])*t)/Sqrt[2]	0	0	0	0	0	0	0
0	0	((3*I + Sqrt[3])*t)/(2*Sqrt[2])	0	-((3*I + Sqrt[3])*t)/4	0	0	((I/2)*(3*I + Sqrt[3])*t)/Sqrt[2]	2*(h + U)	(I/4)*(3*I + Sqrt[3])*t	0	0	0	0	((-3*I + Sqrt[3])*t)/2	0
0	0	0	-((-3*I + Sqrt[3])*t)/4	0	-(Sqrt[3/2]*t)	Sqrt[3/2]*t	0	(-I/4)*(-3*I + Sqrt[3])*t	2*(h + U)	0	0	0	0	0	0
0	((1 + I*Sqrt[3])*t)/(3*Sqrt[2])	0	-(Sqrt[2]*(-3*I + Sqrt[3])*t)/3	0	(-2*t)/Sqrt[3]	((-3*I + Sqrt[3])*t)/3	0	0	0	2*h + U	(I/6)*(5*I + Sqrt[3])*t	0	0	0	-((3*I + Sqrt[3])*t)/(3*Sqrt[2])
(-I/3)*Sqrt[2]*(-I + Sqrt[3])*t	0	0	0	(Sqrt[2]*(3*I + Sqrt[3])*t)/3	0	0	0	0	0	(-I/6)*(-5*I + Sqrt[3])*t	2*h + U	((1 + I)*(-3 + 12*I + (2 - 5*I)*Sqrt[3])*t)/(Sqrt[6]*(3 - Sqrt[3])^(3/2))	((3 + (4 + 3*I)*Sqrt[3])*t)/(3*Sqrt[2*(3 + Sqrt[3])])	0	0
0	(((1 + 3*I)*Sqrt[18 - 6*Sqrt[3]] + (5 - 3*I)*Sqrt[6 - 2*Sqrt[3]])*t)/(2*Sqrt[6]*(-3 + Sqrt[3]))	0	0	0	0	0	0	0	0	0	((1 - I)*(-3 - 12*I + (2 + 5*I)*Sqrt[3])*t)/(Sqrt[6]*(3 - Sqrt[3])^(3/2))	2*h	0	0	((-1/2 + I/2)*(Sqrt[18 - 6*Sqrt[3]] + (2 - I)*Sqrt[6 - 2*Sqrt[3]])*t)/(Sqrt[2]*(-3 + Sqrt[3]))
0	((-3 + 9*I + (5 + 3*I)*Sqrt[3])*t)/(6*Sqrt[3 + Sqrt[3]])	0	0	0	0	0	0	0	0	0	((3 + (4 - 3*I)*Sqrt[3])*t)/(3*Sqrt[2*(3 + Sqrt[3])])	0	2*h	0	((1/2 + I/2)*(-2 - I + Sqrt[3])*t)/Sqrt[3 + Sqrt[3]]
0	((-3*I + Sqrt[3])*t)/4	0	(-I/2)*(-3*I + Sqrt[3])*t	0	((3 + I*Sqrt[3])*t)/(2*Sqrt[2])	((I/2)*(I + Sqrt[3])*t)/Sqrt[2]	0	((3*I + Sqrt[3])*t)/2	0	0	0	0	0	2*h + U	((3 + I*Sqrt[3])*t)/4
-((3*I + Sqrt[3])*t)/12	0	Sqrt[2]*(1 + I*Sqrt[3])*t	0	(t - I*Sqrt[3]*t)/2	0	0	0	0	0	-((-3*I + Sqrt[3])*t)/(3*Sqrt[2])	0	((1 + 3*I)/Sqrt[12 - 4*Sqrt[3]] + ((1 + I)*Sqrt[9 - 3*Sqrt[3]])/(6 - 2*Sqrt[3]))*t	((-1 + 3*I + (1 - I)*Sqrt[3])*t)/(2*Sqrt[3 + Sqrt[3]])	((3 - I*Sqrt[3])*t)/4	2*h + U