A photo-electric absorption using Wisconsin (Morrison and McCammon; ApJ 270, 119) cross-sections.
where 
(E) is the photo-electric cross-section (NOT including Thomson
scattering). Note that this model uses the Anders & Ebihara relative
abundances (1982, Geochimica et Cosmochimica Acta 46, 2363) regardless
of the abund command.
par1 = equivalent hydrogen column (in units of 10atoms/cm
)