Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Photoionization of atoms and molecules studied by Crank-Nicolson method   Crank-Nicolson (C-N) Method combined with $ B $-spline basis set can be used
in both time-dependent and time-independent calculations of the photoionization
cross sections of atoms and molecules. For time-independent systems, it is
found that C-N method in imaginary-time propagation (ITP) can converge directly
to not only the ground state, but also excited and continuum states by
controlling the time step size. The C-N method can also be directly applied in
time-dependent calculations. Both time-dependent and time-independent
calculations agree very well with previous results. This method can also be
extended to two-electron systems directly.

24
The categories of this paper are: dg-ga
35
The categories of this paper are: mtrl-th
31
The categories of this paper are: ao-sci
9
The categories of this paper are: nlin
20
The categories of this paper are: acc-phys
1
The categories of this paper are: cs
21
The categories of this paper are: adap-org
7
The categories of this paper are: hep-th
12
The categories of this paper are: nucl-th
22
The categories of this paper are: chao-dyn
25
The categories of this paper are: patt-sol
11
The categories of this paper are: hep-lat
30
The categories of this paper are: q-alg
33
The categories of this paper are: plasm-ph
19
The categories of this paper are: eess
6
The categories of this paper are: astro-ph