## Angle-dependent strong-field molecular ionization rates with tuned range-separated time-dependent density functional theory

## Abstract

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-fieldmore »

- Authors:

- Louisiana State Univ., Baton Rouge, LA (United States). Dept. of Chemistry
- Louisiana State Univ., Baton Rouge, LA (United States). Dept. of Physics and Astronomy
- Louisiana State Univ., Baton Rouge, LA (United States). Center for Computation and Technology, Dept. of Chemistry

- Publication Date:

- Research Org.:
- Louisiana State Univ., Baton Rouge, LA (United States)

- Sponsoring Org.:
- USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)

- OSTI Identifier:
- 1467880

- Alternate Identifier(s):
- OSTI ID: 1315846

- Grant/Contract Number:
- SC0012462

- Resource Type:
- Accepted Manuscript

- Journal Name:
- Journal of Chemical Physics

- Additional Journal Information:
- Journal Volume: 145; Journal Issue: 9; Journal ID: ISSN 0021-9606

- Publisher:
- American Institute of Physics (AIP)

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

### Citation Formats

```
Sissay, Adonay, Abanador, Paul, Mauger, François, Gaarde, Mette, Schafer, Kenneth J., and Lopata, Kenneth. Angle-dependent strong-field molecular ionization rates with tuned range-separated time-dependent density functional theory. United States: N. p., 2016.
Web. doi:10.1063/1.4961731.
```

```
Sissay, Adonay, Abanador, Paul, Mauger, François, Gaarde, Mette, Schafer, Kenneth J., & Lopata, Kenneth. Angle-dependent strong-field molecular ionization rates with tuned range-separated time-dependent density functional theory. United States. doi:10.1063/1.4961731.
```

```
Sissay, Adonay, Abanador, Paul, Mauger, François, Gaarde, Mette, Schafer, Kenneth J., and Lopata, Kenneth. Fri .
"Angle-dependent strong-field molecular ionization rates with tuned range-separated time-dependent density functional theory". United States. doi:10.1063/1.4961731. https://www.osti.gov/servlets/purl/1467880.
```

```
@article{osti_1467880,
```

title = {Angle-dependent strong-field molecular ionization rates with tuned range-separated time-dependent density functional theory},

author = {Sissay, Adonay and Abanador, Paul and Mauger, François and Gaarde, Mette and Schafer, Kenneth J. and Lopata, Kenneth},

abstractNote = {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. In conclusion, 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.},

doi = {10.1063/1.4961731},

journal = {Journal of Chemical Physics},

number = 9,

volume = 145,

place = {United States},

year = {2016},

month = {9}

}

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