# An Orbital Basis Set for Double Photoionization of Atoms and Molecules.
> 原子・分子の二重光イオン化における軌道基底セットの開発


## Abstract

Theoretical descriptions of one-photon double photoionization have historically been confined to atoms and diatomic molecules due to the computational burden of large grid-based representations of doubly ionized continuum wave functions. This study introduces an energy-adapted orbital basis set strategy that reduces the dimensionality of such representations and enables larger time steps in time-dependent computational frameworks for double ionization. An algorithm exploiting the diagonal structure of two-electron integrals in the grid basis is also presented, substantially accelerating transformations between grid and orbital representations. Benchmark comparisons for hydrogen and beryllium atoms, as well as the hydrogen molecule, demonstrate strong agreement with established theoretical results, including triply differential cross sections that characterize angular distributions and energy sharing among all particles in the molecular frame.

### Mechanism

An energy-adapted orbital basis reduces grid representation dimensionality, while an algorithm exploiting the diagonal character of two-electron integrals in the grid basis accelerates transformations between grid and orbital representations.

## Bibliographic

- **Authors**: Bello RY, Yip FL, Streeter Z, Lucchese R, McCurdy CW
- **Journal**: J Chem Theory Comput
- **Year**: 2024 (2024-10-22)
- **PMID**: [39395004](https://pubmed.ncbi.nlm.nih.gov/39395004/)
- **DOI**: [10.1021/acs.jctc.4c00929](https://doi.org/10.1021/acs.jctc.4c00929)
- **PMC**: [PMC11500310](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11500310/)
- **Study type**: other
- **Delivery route**: not specified
- **Effect reported**: not assessed

## Delivery context

The delivery route is not clearly identifiable from this paper. For hydrogen intake, inhalation is the most efficient route; inhalation, however, carries explosion risk (empirical LFL of 10%; high-concentration devices are not recommended).

## Safety notes

The delivery route is not clearly identifiable from this paper. For hydrogen intake, inhalation is the most efficient route; inhalation, however, carries explosion risk (empirical LFL of 10%; high-concentration devices are not recommended).

See also:
- [Inhalation concentration and LFL / UFL](https://h2-papers.org/en/safety-notes/inhalation-concentration)
- [Consumer Affairs Agency accident cases](https://h2-papers.org/en/safety-notes/accident-cases)

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> **Cite as**: H2 Papers — PMID 39395004. https://h2-papers.org/en/papers/39395004
> **Source**: PubMed PMID [39395004](https://pubmed.ncbi.nlm.nih.gov/39395004/)