### Abstract

Original language | English |
---|---|

Article number | 1597989 |

Journal | Molecular Physics |

Number of pages | 13 |

ISSN | 0026-8976 |

DOIs | |

Publication status | Published - 30 Mar 2019 |

MoE publication type | A1 Journal article-refereed |

### Fields of Science

- 116 Chemical sciences
- 114 Physical sciences
- Magnetic field
- finite element
- Hartree-Fock
- intermediate regime
- basis set truncation error
- SELF-CONSISTENT-FIELD
- GAUSSIAN-BASIS SETS
- HYDROGEN MOLECULE
- GROUND-STATE
- HARTREE-FOCK
- HELIUM ATOM
- POSITIVE-ION
- BORON
- MANIFOLD
- VALENCE

### Cite this

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**Fully numerical electronic structure calculations on diatomic molecules in weak to strong magnetic fields.** / Lehtola, Susi; Dimitrova, Maria; Sundholm, Dage .

Research output: Contribution to journal › Article › Scientific › peer-review

TY - JOUR

T1 - Fully numerical electronic structure calculations on diatomic molecules in weak to strong magnetic fields

AU - Lehtola, Susi

AU - Dimitrova, Maria

AU - Sundholm, Dage

PY - 2019/3/30

Y1 - 2019/3/30

N2 - We present fully numerical electronic structure calculations on diatomic molecules exposed to an external magnetic field at the unrestricted Hartree-Fock limit, using a modified version of a recently developed finite-element programme, HelFEM. We have performed benchmark calculations on a few low-lying states of H-2, HeH+, LiH, BeH+, BH and CH+ as a function of the strength of an external magnetic field parallel to the molecular axis. The employed magnetic fields are in the range of B = [0, 10] B-0 atomic units, where B-0 approximate to 2.35 x 10(5) T. We have compared the results of the fully numerical calculations to ones obtained with the LONDON code using a large uncontracted gauge-including Cartesian Gaussian (GICG) basis set with exponents adopted from the Dunning aug-cc-pVTZ basis set. By comparison to the fully numerical results, we find that the basis set truncation error (BSTE) in the GICG basis is of the order of 1 kcal/mol at zero field, that the BSTE grows rapidly in increasing magnetic field strength, and that the largest BSTE at B = 10 B-0 exceeds 1000 kcal/mol. Studies in larger Gaussian-basis sets suggest that reliable results can be obtained in GICG basis sets at fields stronger than B = B-0, provided that enough higher-angular-momentum functions are included in the basis.

AB - We present fully numerical electronic structure calculations on diatomic molecules exposed to an external magnetic field at the unrestricted Hartree-Fock limit, using a modified version of a recently developed finite-element programme, HelFEM. We have performed benchmark calculations on a few low-lying states of H-2, HeH+, LiH, BeH+, BH and CH+ as a function of the strength of an external magnetic field parallel to the molecular axis. The employed magnetic fields are in the range of B = [0, 10] B-0 atomic units, where B-0 approximate to 2.35 x 10(5) T. We have compared the results of the fully numerical calculations to ones obtained with the LONDON code using a large uncontracted gauge-including Cartesian Gaussian (GICG) basis set with exponents adopted from the Dunning aug-cc-pVTZ basis set. By comparison to the fully numerical results, we find that the basis set truncation error (BSTE) in the GICG basis is of the order of 1 kcal/mol at zero field, that the BSTE grows rapidly in increasing magnetic field strength, and that the largest BSTE at B = 10 B-0 exceeds 1000 kcal/mol. Studies in larger Gaussian-basis sets suggest that reliable results can be obtained in GICG basis sets at fields stronger than B = B-0, provided that enough higher-angular-momentum functions are included in the basis.

KW - 116 Chemical sciences

KW - 114 Physical sciences

KW - Magnetic field

KW - finite element

KW - Hartree-Fock

KW - intermediate regime

KW - basis set truncation error

KW - SELF-CONSISTENT-FIELD

KW - GAUSSIAN-BASIS SETS

KW - HYDROGEN MOLECULE

KW - GROUND-STATE

KW - HARTREE-FOCK

KW - HELIUM ATOM

KW - POSITIVE-ION

KW - BORON

KW - MANIFOLD

KW - VALENCE

U2 - 10.1080/00268976.2019.1597989

DO - 10.1080/00268976.2019.1597989

M3 - Article

JO - Molecular Physics

JF - Molecular Physics

SN - 0026-8976

M1 - 1597989

ER -