Theoretical Studies Of Ionization Dynamics For Linear Molecules In Intense Laser Fields

The multi-electron dynamics of atoms and molecules in the intense laser field, have attracted great attentions due to the development of laser technology. It is well known that the investigation of many-electron dynamics is a tremendous challenge for ab-initio meth-ods. Moreover, some experimental phenomena need to be explored further, which result from many-electron effects. Thus, a number of new approaches need to be developed to study multi-electron dynamics in the strong laser fields, and one of them is time-dependent Hartree-Fock(TDHF) theory. In our work, time-dependent Hartree-Fock theory has been de-veloped further based on single-center method, B-splines and finite element discrete-variable representation(FE-DVR). Furthermore, it has been applied to studying electronic structure of atoms and linear molecules, and the electron dynamics of linear molecules in the intense laser field. The main constants are as following:(1) Based on single-center method and B-splines, we take account of the vibration for Hydrogen molecular ion, and check the validity of Born-Oppenheimer approximation in strong magnetic fields. Furthermore, we perform calculations for vibrational transition spectra of Hydrogen molecular ion in magnetic fields, and find that the relative difference of vibrational frequency is10.8%for harmonic approximation.(2) We have carried out Hartree-Fock calculations on some typical atoms and diatomic molecules associating with B-splines and one-center method. Because the cusps could be handled properly by B-splines, good accuracy is achieved for the orbital energies and to-tal energies of atoms(He, Be and Ne) and diatomic molecules(H2, N2, LiH and CO) with moderate basis sets.(3) B-splines and one-center method could describe continuum state wave functions appropriately, and it is natural to extend single-center method to the investigation of lin-ear many-atom molecules. Thus, we perform Hartree-Fock calculations for CO2, construct single-active-electron potential based on the above approaches, and study the alignment-dependent ionization of CO2in the strong laser fields. A reasonable agreement is found between our data and other theoretical results, while discrepancies exist between our values and experimental data.(4) We have developed TDHF theory by combining B-splines and FE-DVR base, which has also been adopted to study many-electron dynamics of C2H2in the few-cycle pulses. The results show that the ionization of inner electrons is stronger than that of highest occupied molecular orbital(HOMO) for intense laser fields, due to the inner orbital charge distribution parallel to the polarization of laser field. In addition, the ionization of inner orbitals increases with enhancing laser fields, and the orbital energy of HOMO becomes larger, which leads to the suppressing ionization for HOMO.