Relativistic Effects in Chemistry

Almlöf, Jan; Gropen, Odd

doi:10.1002/9780470125854.ch4

Cited by 34 publications

(16 citation statements)

References 101 publications

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“…(1), a scalar relativistic part containing the mass-velocity and Darwin terms, and a spin-orbit coupling Hamiltonian. 25,27 We note that scalar relativistic effects, when important, are often accounted for in quantum chemistry by using effective core potentials. 28 Incorporating the SOC Hamiltonian in the electronic Hamiltonian, 27,[29][30][31] we obtain a molecular Hamiltonian accounting for the electronic spin s,…”

Section: Theorymentioning

confidence: 99%

“…Including SOC effects in the framework of the timedependent Schrödinger equation necessitates the derivation and approximation of new extended electronic Hamiltonians from the Dirac-Coulomb-Breit equation. 25 The Breit-Pauli Hamiltonian is commonly employed and its most important parts 26 comprise the non-relativistic Hamiltonian of Eq. (1), a scalar relativistic part containing the mass-velocity and Darwin terms, and a spin-orbit coupling Hamiltonian.…”

Section: Theorymentioning

confidence: 99%

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Communication: GAIMS—Generalized Ab Initio Multiple Spawning for both internal conversion and intersystem crossing processes

Curchod

Rauer

Marquetand

et al. 2016

The Journal of Chemical Physics

104

103

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A new approach to molecular dynamics with non-adiabatic and spin-orbit effects with applications to QM/MM simulations of thiophene and selenophene The Journal of Chemical Physics 146, 114101 (2017); 10.1063/1.4978289 THE JOURNAL OF CHEMICAL PHYSICS 144, 101102 (2016) Communication: GAIMS-Generalized Ab Initio Multiple Spawning for both internal conversion and intersystem crossing processes Full multiple spawning is a formally exact method to describe the excited-state dynamics of molecular systems beyond the Born-Oppenheimer approximation. However, it has been limited until now to the description of radiationless transitions taking place between electronic states with the same spin multiplicity. This Communication presents a generalization of the full and ab initio multiple spawning methods to both internal conversion (mediated by nonadiabatic coupling terms) and intersystem crossing events (triggered by spin-orbit coupling matrix elements) based on a spin-diabatic representation. The results of two numerical applications, a model system and the deactivation of thioformaldehyde, validate the presented formalism and its implementation. C 2016 AIP Publishing LLC. [http://dx

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Section: Theorymentioning

confidence: 99%

Section: Theorymentioning

confidence: 99%

Communication: GAIMS—Generalized Ab Initio Multiple Spawning for both internal conversion and intersystem crossing processes

Curchod

Rauer

Marquetand

et al. 2016

The Journal of Chemical Physics

104

103

View full text Add to dashboard Cite

show abstract

“…The work of these theoreticians and that of many others, which followed in the last 40 years, is summarized in textbooks, review articles, and the references cited therein. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] In this time span, relativistic quantum chemical methods were developed which made a reliable calculation of relativistic effects for atoms and molecules possible. A way of describing these developments is by referring to the relativistic Hamiltonian (i.e., the energy operator) used by quantum chemists.…”

Section: Short Historical Overview Of Relativistic Methodsmentioning

confidence: 99%

“…T he identification and understanding of relativistic effects is essential for an expert analysis of the chemistry of heavy and superheavy elements. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] For a long time, relativistic effects were not considered to be important for chemistry because chemical processes and chemical properties are largely determined by the valence electrons of an atom. This belief was based on a misleading interpretation of the so-called mass-velocity effect originally discovered by Einstein 16 when developing the theory of special relativity:…”

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confidence: 99%

Dirac‐exact relativistic methods: the normalized elimination of the small component method

Cremer

Zou

Filatov

2014

WIREs Comput Mol Sci

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Dirac‐exact relativistic methods, i.e., 2‐ or 1‐component methods which exactly reproduce the one‐electron energies of the original 4‐component Dirac method, have established a standard for reliable relativistic quantum chemical calculations targeting medium‐ and large‐sized molecules. Their development was initiated and facilitated in the late 1990s by Dyall's development of the normalized elimination of the small component (NESC). Dyall's work has fostered the conversion of NESC and related (later developed) methods into routinely used, multipurpose Dirac‐exact methods by which energies, first‐order, and second‐order properties can be calculated at computational costs, which are only slightly higher than those of nonrelativistic methods. This review summarizes the development of a generally applicable 1‐component NESC algorithm leading to the calculation of reliable energies, geometries, electron density distributions, electric moments, electric field gradients, hyperfine structure constants, contact densities and Mössbauer isomer shifts, nuclear quadrupole coupling constants, vibrational frequencies, infrared intensities, and static electric dipole polarizabilities. In addition, the derivation and computational possibilities of 2‐component NESC methods are discussed and their use for the calculation of spin‐orbit coupling (SOC) effects in connection with spin‐orbit splittings and SOC‐corrected energies are demonstrated. The impact of scalar relativistic and spin‐orbit effects on molecular properties is presented. WIREs Comput Mol Sci 2014, 4:436–467. This article is categorized under: Electronic Structure Theory > Ab Initio Electronic Structure Methods

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“…These are known to affect practically all atomic or molecular properties, and their importance tends to grow with the atomic mass. [25] In the case of large (typically nonsymmetric) closed-shell systems, such as the ones studied in this work, relativity treatment can be reduced to so-called scalar (or spin-independent) relativistic effects (SREs) [26,27] if errors up to few (typically, tenths of) percentages in interaction energies are tolerable. [28] This is a substantial simplification as the neglect of spin-orbit (SO) coupling makes calculations of extended molecular complexes computationally feasible.…”

mentioning

confidence: 99%

Assessment of scalar relativistic effects on halogen bonding and σ‐hole properties

Kolář

Suchá

Pitoňák

2020

Int J of Quantum Chemistry

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Halogen bond (X-bond) is a noncovalent interaction between a halogen atom and an electron donor. It is often rationalized by a region of the positive electrostatic potential on the halogen atom, so-called σ-hole. The X-bond strength increases with the atomic number of the halogen involved; thus, for heavier halogens, relativistic effects become of concern. This poses a challenge for the quantum chemical description of X-bonded complexes. To quantify scalar relativistic effects (SREs) on the interaction energies and σ-hole properties, we have performed highly accurate coupled-cluster calculations at the complete basis set limit of several X-bonded complexes and their halogenated monomers. We found that the SREs are comparable in magnitude to the effect of the basis set. The nonrelativistic calculations typically underestimate the attraction by up to 5% or 23% for brominated and iodinated complexes, respectively. Counterintuitively, the electron densities at the bond critical points are larger for SRE-free calculations than for the relativistic ones. SREs yield smaller, flatter, and more positive σ-holes. Finally, we highlight the importance of diffuse functions in the basis sets and provide quantitative arguments for using basis sets with pseudopotentials as an affordable alternative to a more rigorous Douglas-Kroll-Hess relativistic theory.

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Relativistic Effects in Chemistry

Cited by 34 publications

References 101 publications

Communication: GAIMS—Generalized Ab Initio Multiple Spawning for both internal conversion and intersystem crossing processes

Communication: GAIMS—Generalized Ab Initio Multiple Spawning for both internal conversion and intersystem crossing processes

Dirac‐exact relativistic methods: the normalized elimination of the small component method

Assessment of scalar relativistic effects on halogen bonding and σ‐hole properties

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