Angle-dependent strong-field molecular ionization rates with tuned range-separated time-dependent density functional theory.
Strong-field ionization and the resulting electronic dynamics are important for a range of processes such as high harmonic generation, photodamage, charge resonance enhanced ionization, and ionization-triggered charge migration. Modeling ionization dynamics in molecular systems from first-principles can be challenging due to the large spatial extent of the wavefunction which stresses the accuracy of basis sets, and the intense fields which require non-perturbative time-dependent electronic structure methods. In this paper, we develop a time-dependent density functional theory approach which uses a Gaussian-type orbital (GTO) basis set to capture strong-field ionization rates and dynamics in atoms and small molecules. This involves propagating the electronic density matrix in time with a time-dependent laser potential and a spatial non-Hermitian complex absorbing potential which is projected onto an atom-centered basis set to remove ionized charge from the simulation. For the density functional theory (DFT) functional we use a tuned range-separated functional LC-PBE*, which has the correct asymptotic 1/r form of the potential and a reduced delocalization error compared to traditional DFT functionals. Ionization rates are computed for hydrogen, molecular nitrogen, and iodoacetylene under various field frequencies, intensities, and polarizations (angle-dependent ionization), and the results are shown to quantitatively agree with time-dependent Schrödinger equation and strong-field approximation calculations. This tuned DFT with GTO method opens the door to predictive all-electron time-dependent density functional theory simulations of ionization and ionization-triggered dynamics in molecular systems using tuned range-separated hybrid functionals.
Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, USA.
Adonay
A
Sissay
Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803, USA.
Paul
P
Abanador
Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803, USA.
François
F
Mauger
Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803, USA.
Mette
M
Gaarde
Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803, USA.
Kenneth J
KJ
Schafer
Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, USA.
Kenneth
K
Lopata