# Quantum locality and equilibrium properties in low-temperature parahydrogen: a multiscale simulation study.
> 低温パラ水素における量子局所性と平衡特性：マルチスケールシミュレーション研究


## Abstract

Parahydrogen, the spin-zero singlet form of molecular hydrogen, exists as a fluid between approximately 14 and 25 K. Classical simulation approaches produce unphysical solidification at these temperatures, making quantum mechanical treatment necessary. This study applied the classical-quantum adaptive resolution scheme (AdResS) to examine how far quantum delocalization effects extend spatially within the bulk fluid. A spherical quantum region of variable size was embedded in a classically described surrounding medium with quantum-derived effective potentials, connected via open thermodynamic boundaries. Pair distribution functions were computed for several quantum region sizes. The findings indicate that, across the 14–25 K temperature range, the quantum structural characteristics of parahydrogen are spatially local, meaning that an explicit quantum description of the entire bulk is not required to capture accurate equilibrium properties.

### Mechanism

Using the AdResS adaptive resolution method, a quantum-treated spherical region was coupled to a classically described bulk via open boundaries; pair distribution functions computed at varying quantum region sizes demonstrated that quantum delocalization effects in parahydrogen are spatially local at 14–25 K.

## Bibliographic

- **Authors**: Potestio R, Delle Site L
- **Journal**: J Chem Phys
- **Year**: 2012 (2012-02-07)
- **PMID**: [22320719](https://pubmed.ncbi.nlm.nih.gov/22320719/)
- **DOI**: [10.1063/1.3678587](https://doi.org/10.1063/1.3678587)
- **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 22320719. https://h2-papers.org/en/papers/22320719
> **Source**: PubMed PMID [22320719](https://pubmed.ncbi.nlm.nih.gov/22320719/)