## PHOENIX

### Physics

Some more or less important physical features of `PHOENIX` are:

- 1D plane parallel/spherical symmetric or 3D using different geometries radiative transfer
- static or (up to relativistic) expanding media
- the radiative transfer equation is solved using operator splitting
- multilevel NLTE calculations for atoms with a total of more than 10000 levels and 100000 primary lines
- the NLTE rate equations are solved using operator splitting techniques
- usage of four atomic databases with NLTE transitions: CHIANTI Version 3 and 4, APED (ATOMDB) and the primary PHOENIX database
- line blanketing and background opacities are included by design
- over 650 species in the EOS including atoms, ions, molecules and grains
- depth dependent Voigt profiles for Stark and van der Waals broadening
- dynamical opacity sampling (dOS) of about 42 Million atomic lines and over 550 Million (and growing) molecular lines (more than 10GB worth of data)
- spectra can be calculated for any desired resolution (standard are 20000 to 500000 wavelength points spread from the UV to the radio)
- ... and more ..

### Implementation

`PHOENIX` is a parallelized Fortran 95 code with parts written in C (I/O) and C++ (high precision arithmetic using the QD library). The parallel computing is implemented using MPI (and partially openMP), for example Open MPI.