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Strong field ionization of molecules by intense laser pulses can be simulated by time-dependent configuration interaction (TD-CI) with a complex absorbing potential (CAP). Standard molecular basis sets need to be augmented with several sets of diffuse functions for effective interaction with the CAP. This dramatically increases the number of configurations and the cost of the TD-CI simulations as the size of the molecules increases. The cost can be reduced by making use of spin symmetry and by employing an orbital energy cut-off to limit the number of virtual orbitals used to construct the excited configurations. Greater reductions in the number of virtual orbitals can be obtained by examining their interaction with the absorbing potential during simulations and their contributions to the strong field ionization rate. This can be determined from the matrix elements of the absorbing potential and the TD-CI coefficients from test simulations. Compared to a simple 3 hartree cut-off in the orbital energies, these approaches reduce the number of virtual orbitals by 20% - 35% for neutral molecules and 5%-10% for cations. As a result, the cost of simulations is reduced by 35% - 60% for neutral molecules and 5% - 10% for cations. The number of virtual orbitals needed can also be estimated by second-order perturbation theory without the need for test simulations. The number of virtual orbitals can be reduced further by adapting orbitals to the laser field using natural orbitals derived from test simulations. This is particularly effective for cations, yielding reductions of more than 20%.
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njdowdy/tpt-taxonomy: TPT Taxonomic Resource v2.0.0
This is the second public release of the taxonomic resources generated for the Terrestrial Parasite Tracker project. Some names given by list providers may be omitted due to being flagged for curatorial review for various reasons. Funded by National Science Foundation (US) grant DBI-1901932
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- Award ID(s):
- 1901932
- PAR ID:
- 10650735
- Publisher / Repository:
- Zenodo
- Date Published:
- Edition / Version:
- v2.0.0
- Subject(s) / Keyword(s):
- taxonomy biodiversity informatics
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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