  We use the PHOENIX code package to model the X-ray spectrum of Nova V4743
Sagittarii observed with the LETGS onboard the Chandra satellite on 19 March
2003. To analyze nova atmospheres and related systems with an underlying
nuclear burning envelope at X-ray wavelengths, it was necessary to update the
code with new microphysics. We demonstrate that the X-ray emission is dominated
by thermal bremsstrahlung and that the hard X-rays are dominated by Fe and N
absorption. Preliminary models are calculated assuming solar abundances. It is
shown that the models can be used to determine element abundances in the nova
ejecta by increasing the absorption in the shell.
