We present newly calculated low-temperature opacities for gas with a primordial chemical composition .
In contrast to earlier calculations which took a pure metal-free Hydrogen/Helium mixture , we take into account the small fractions of Deuterium and Lithium as resulting from Standard Big Bang Nucleosynthesis .
Our opacity tables cover the density range -16 < \log \rho \hskip { 2.845276 pt } [ \textup { g } \textup { cm } ^ { -3 } ] < -2 and temperature range of 1.8 < \log T \hskip { 2.845276 pt } [ \textup { K } ] < 4.6 , while previous tables were usually restricted to T > 10 ^ { 3 } \mathrm { K } .
We find that , while the presence of Deuterium does not significantly alter the opacity values , the presence of Lithium gives rise to major modifications of the opacities , at some points increasing it by approximately 2 orders of magnitude relative to pure Hydrogen/Helium opacities .