3 research outputs found
Precise Calculation of Single and Double Ionization of Hydrogen Molecule in Intense Laser Pulses
A new simulation box setup is introduced for the precise description of the
wavepacket evolution of two electronic systems in intense laser pulses. In this
box, the regions of the hydrogen molecule H, and singly and doubly
ionized species, H and H, are well recognized and their
time-dependent populations are calculated at different laser field intensities.
In addition, some new regions are introduced and characterized as quasi-double
ionization and their time-dependencies on the laser field intensity are
calculated and analyzed. The adopted simulation box setup is special in that it
assures proper evaluation of the second ionization. In this study, the dynamics
of the electrons and nuclei of the hydrogen molecule are separated based on the
adiabatic approximation. The time-dependent Schr\"{o}dinger and Newton
equations are solved simultaneously for the electrons and the nuclei,
respectively. Laser pulses of 390 nm wavelength at four different intensities
(i.e. , , , and W cm) are used in these simulations. Details of the
central H region is also presented and discussed. This region is divided
into four sub-regions related to the ionic state HH and covalent
(natural) state HH. The effect of the motion of nuclei on the enhanced
ionization is discussed. Finally, some different time-dependent properties are
calculated and their dependencies on the intensity of the laser pulse are
studied, and their correlations with the populations of different regions are
analyzed.Comment: 30 pages, 17 figure
Nuclear classical dynamics of H in intense laser field
In the first part of this paper, the different distinguishable pathways and
regions of the single and sequential double ionization are determined and
discussed. It is shown that there are two distinguishable pathways for the
single ionization and four distinct pathways for the sequential double
ionization. It is also shown that there are two and three different regions of
space which are related to the single and double ionization respectively. In
the second part of the paper, the time dependent Schr\"{o}dinger and Newton
equations are solved simultaneously for the electrons and the nuclei of H
respectively. The electrons and nuclei dynamics are separated on the base of
the adiabatic approximation. The soft-core potential is used to model the
electrostatic interaction between the electrons and the nuclei. A variety of
wavelengths (390 nm, 532 nm and 780 nm) and intensities (
and ) of the ultrashort intense laser
pulses with a sinus second order envelope function are used. The behaviour of
the time dependent classical nuclear dynamics in the absence and present of the
laser field are investigated and compared. In the absence of the laser field,
there are three distinct sections for the nuclear dynamics on the electronic
ground state energy curve. The bond hardening phenomenon does not appear in
this classical nuclear dynamics simulation.Comment: 16 pages, 7 figure