DDB_a = -3.812330
DDB_b = 34.256065
DDB_c = -2.844881
DDB_d = -2.285745
DDB_e = 32.665721
DDB_f = 27.741413
DDB_g =  0.0
a0          = 3.98596961387263
Z_star      = 10.33
epsilon_inf = 6.8691464565