Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Non-equilibrium Equation of State in stellar atmospheres   In the stellar chromospheres, radiative energy transport is dominated by only
the strongest spectral lines. For these lines, the approximation of local
thermodynamic equilibrium (LTE) is known to be very inaccurate, and a state of
equilibrium cannot be assumed in general. To calculate the radiative energy
transport under these conditions, the population evolution equation must be
evaluated explicitly, including all time-dependent terms. We develop a
numerical method to solve the evolution equation for the atomic-level
populations in a time-implicit way, keeping all time-dependent terms to first
order. We show that the linear approximation of the time dependence of the
populations can handle very large time steps without losing the accuracy. We
reproduce the benchmark solutions from earlier, well-established works in terms
of non-LTE kinetic equilibrium solution and typical ionization/recombination
time-scales in the solar chromosphere.

16
The categories of this paper are: stat
35
The categories of this paper are: mtrl-th
19
The categories of this paper are: eess
15
The categories of this paper are: nucl-ex
28
The categories of this paper are: alg-geom
7
The categories of this paper are: hep-th
10
The categories of this paper are: q-bio
34
The categories of this paper are: chem-ph
30
The categories of this paper are: q-alg
17
The categories of this paper are: q-fin
8
The categories of this paper are: hep-ex
18
The categories of this paper are: econ
14
The categories of this paper are: math-ph
21
The categories of this paper are: adap-org
27
The categories of this paper are: comp-gas
29
The categories of this paper are: funct-an