Description of molecular dynamics in intense laser fields by the time-dependent adiabatic state approach: Application to simultaneous two-bond dissociation of CO2 and its control
ABSTRACT We theoretically investigated the dynamics of structural deformations of CO(2) and its cations in near-infrared intense laser fields (approximately 10(15) W cm(-2)) by using the time-dependent adiabatic state approach. To obtain "field-following" adiabatic potentials for nuclear dynamics, the electronic Hamiltonian including the interaction with the instantaneous laser electric field is diagonalized by the multiconfiguration self-consistent-field molecular orbital method. In the CO(2) and CO(2+) stages, ionization occurs before the field intensity becomes high enough to deform the molecule. In the CO(2)(2+) stage, simultaneous symmetric two-bond stretching occurs as well as one-bond stretching. Two-bond stretching is induced by an intense field in the lowest time-dependent adiabatic state |1> of CO(2)(2+), and this two-bond stretching is followed by the occurrence of a large-amplitude bending motion mainly in the second-lowest adiabatic state |2> nonadiabatically created at large internuclear distances by the field from |1>. It is concluded that the experimentally observed stretched and bent structure of CO(2)(3+) just before Coulomb explosions originates from the structural deformation of CO(2)(2+). We also show in this report that the concept of "optical-cycle-averaged potential" is useful for designing schemes to control molecular (reaction) dynamics, such as dissociation dynamics of CO(2), in intense fields. The present approach is simple but has wide applicability for analysis and prediction of electronic and nuclear dynamics of polyatomic molecules in intense laser fields.
- Advances in Atomic, Molecular, and Optical Physics 01/2005; 50:219-286. DOI:10.1016/S1049-250X(05)80010-2
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ABSTRACT: A ground state wave function of a one-dimensional H2 molecule is derived numerically by the extended multi-configuration time-dependent Hartree-Fock (MCTDHF) method. The electronic orbitals and the amplitudes for the nuclear motion constituting the ground-state wave function are derived by solving the coupled equations of motion by the imaginary time propagation. Comparisons with the results obtained by the Born-Huang (BH) expansion method as well as with the exact wave function reveal that the memory size required in the extended MCTDHF method is about two orders of magnitude smaller than in the BH expansion method.Chemical Physics Letters 03/2014; 595. DOI:10.1016/j.cplett.2014.01.055
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ABSTRACT: The non-sequential three-body Coulomb explosion, CS23+→S++C++S+, in an intense laser field (0.2 PW/cm2, 60 fs) is studied by the coincidence momentum imaging of the fragment ions. The observed angular distribution of the momentum vectors of the two S+ ions, p1(S+) and p2(S+), exhibits a peak at an angle as small as θ12∼140°, showing that the nuclear motion is induced along the bending coordinate to a large extent prior to the explosion. On the other hand, the difference between their absolute values, Δp12=|p1(S+)|−|p2(S+)|, has a sharp distribution peaked at Δp12=0, suggesting that the symmetric stretching motion dominates over the antisymmetric stretching motion in the laser field. Based on the energy dependence of the momentum vector correlation, the characteristic nuclear dynamics of CS2 on the light-dressed potential energy surfaces in an intense laser field is discussed.Chemical Physics Letters 04/2004; 388(1):1-6. DOI:10.1016/j.cplett.2004.01.128