Viscoelastic model parameters in LS-Dyna

I'm using elastic solid elements to model wave propagation in an
structure in LS-DYNA. I need to add the effect of dissipation in the
system by using viscoelastic material model (MAT_006). All I know from
my material is storage & loss modulus (E=E'+E"*i). I was wondering
how can I transform these parameters into G0, GI and BETA needed by
MAT_006 (G = Gi + (G0-Gi) *交货p(-beta*t))?