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

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Abstract

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.
Original languageEnglish
Article number1597989
JournalMolecular Physics
Number of pages13
ISSN0026-8976
DOIs
Publication statusPublished - 30 Mar 2019
MoE publication typeA1 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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title = "Fully numerical electronic structure calculations on diatomic molecules in weak to strong magnetic fields",
abstract = "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.",
keywords = "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",
author = "Susi Lehtola and Maria Dimitrova and Dage Sundholm",
year = "2019",
month = "3",
day = "30",
doi = "10.1080/00268976.2019.1597989",
language = "English",
journal = "Molecular Physics",
issn = "0026-8976",
publisher = "TAYLOR & FRANCIS LTD",

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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 -