TY  - JOUR
A1  - Witzorky, Christoph
A1  - Paramonov, Guennaddi
A1  - Bouakline, Foudhil
A1  - Jaquet, Ralph
A1  - Saalfrank, Peter
A1  - Klamroth, Tillmann
T1  - Gaussian-type orbital calculations for high harmonic generation in vibrating molecules
BT  - Benchmarks for H-2(+)
JF  - Journal of chemical theory and computation
N2  - The response of the hydrogen molecular ion, H-2(+), to few-cycle laser pulses of different intensities is simulated. To treat the coupled electron-nuclear motion, we use adiabatic potentials computed with Gaussian-type basis sets together with a heuristic ionization model for the electron and a grid representation for the nuclei. Using this mixed-basis approach, the time-dependent Schrodinger equation is solved, either within the Born-Oppenheimer approximation or with nonadiabatic couplings included. The dipole response spectra are compared to all-grid-based solutions for the three-body problem, which we take as a reference to benchmark the Gaussian-type basis set approaches. Also, calculations employing the fixed-nuclei approximation are performed, to quantify effects due to nuclear motion. For low intensities and small ionization probabilities, we get excellent agreement of the dynamics using Gaussian-type basis sets with the all-grid solutions. Our investigations suggest that high harmonic generation (HHG) and high-frequency response, in general, can be reliably modeled using Gaussian-type basis sets for the electrons for not too high harmonics. Further, nuclear motion destroys electronic coherences in the response spectra even on the time scale of about 30 fs and affects HHG intensities, which reflect the electron dynamics occurring on the attosecond time scale. For the present system, non-Born-Oppenheimer effects are small. The Gaussian-based, nonadiabatically coupled, time-dependent multisurface approach to treat quantum electron-nuclear motion beyond the non-Born-Oppenheimer approximation can be easily extended to approximate wavefunction methods, such as time-dependent configuration interaction singles (TD-CIS), for systems where no benchmarks are available.
KW  - Basis sets
KW  - Chemical calculations
KW  - Ionization
KW  - Lasers
KW  - Quantum mechanics
Y1  - 2021
U6  - https://doi.org/10.1021/acs.jctc.1c00837
SN  - 1549-9618
SN  - 1549-9626
VL  - 17
IS  - 12
SP  - 7353
EP  - 7365
PB  - American Chemical Society
CY  - Washington
ER  -