Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Solution of the time-dependent Dirac equation for describing multiphoton
  ionization of highly-charged hydrogenlike ions   A theoretical study of the intense-field multiphoton ionization of
hydrogenlike systems is performed by solving the time-dependent Dirac equation
within the dipole approximation. It is shown that the velocity-gauge results
agree to the ones in length gauge only if the negative-energy states are
included in the time propagation. On the other hand, for the considered laser
parameters, no significant difference is found in length gauge if the
negative-energy states are included or not. Within the adopted dipole
approximation the main relativistic effect is the shift of the ionization
potential. A simple scaling procedure is proposed to account for this effect.

9
The categories of this paper are: nlin
12
The categories of this paper are: nucl-th
20
The categories of this paper are: acc-phys
28
The categories of this paper are: alg-geom
7
The categories of this paper are: hep-th
29
The categories of this paper are: funct-an
10
The categories of this paper are: q-bio
18
The categories of this paper are: econ
1
The categories of this paper are: cs
34
The categories of this paper are: chem-ph
16
The categories of this paper are: stat
36
The categories of this paper are: cmp-lg
23
The categories of this paper are: solv-int
8
The categories of this paper are: hep-ex
32
The categories of this paper are: atom-ph
27
The categories of this paper are: comp-gas