Computational Methods: Lanthanides and Actinides

Dolg, Michael; Cao, Xiaoyan

doi:10.1002/0470862106.ia640

Cited by 3 publications

(2 citation statements)

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“…The obvious context in which to perform the extension uses the relativistic effective core potential (RECP) method [21][22][23]. However, the new nonlinear expansion formulation is not specific to the RECP method.…”

Section: Discussionmentioning

confidence: 99%

Spin–orbit interaction with nonlinear wave functions

Brozell

Shepard

Zhang

2007

Int J of Quantum Chemistry

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ABSTRACT:The computation of the spin-orbit interaction is discussed for electronic wave functions expressed in the new nonlinear expansion form. This form is based on spin eigenfunctions using the graphical unitary group approach (GUGA). The nodes of a Shavitt graph in GUGA are connected by arcs, and a Configuration State Function (CSF) is represented as a walk along arcs from the vacuum node to a head node. The wave function is a linear combination of product functions each of which is a linear combination of all CSFs, wherein each CSF coefficient is a product of nonlinear arc factors. When the spin-orbit interaction is included the Shavitt graph is a union of single-headed Shavitt graphs each with the same total number of electrons and orbitals. Thus spin-orbit Shavitt graphs are multiheaded. For full-CI multiheaded Shavitt graphs, analytic expressions are presented for the number of walks, the number of nodes, the number of arcs, and the number of node pairs in the associated auxiliary pair graph.

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Section: Discussionmentioning

confidence: 99%

Spin–orbit interaction with nonlinear wave functions

Brozell

Shepard

Zhang

2007

Int J of Quantum Chemistry

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“…However, population analyses of the CASSCF results indicated (close to) integer occupations of the Ln-N bonding orbitals; hence, the multiconfiguration is manifested practically in the distribution of the 4f electrons among the 4f orbitals. Due to the generally negligible role of 4f orbitals in the bonding, [62][63][64][65] DFT in conjunction with 4f-in-valence pseudopotentials [39,40] can be expected to model the bonding interactions and several molecular properties (eg, geometries) reliably. The application of 4f-in-valence pseudopotentials allows the valence basis set the flexibility required for 4f !…”

Section: Casscf Calculations For the Assessment Of Multiconfiguratimentioning

confidence: 99%

Structure and bonding of lanthanide dinitrogen complexes, Ln(N₂)_1‐8

Kovács

2019

Int J of Quantum Chemistry

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Lanthanide dinitrogen complexes, Ln(N 2 ) x (x = 1-8), were investigated by Density Functional Theory computations using the B3LYP exchange-correlation functional in conjunction with quasirelativistic pseudopotentials for Ln. After a recent study on the lanthanum complexes (A. Kovács, Structural Chemistry 2018, 29, 1825, the present study aimed to probe the changes upon variously filled 4f subshells of Ln on the structures, stabilities, and bonding properties in related complexes of Nd, Ho, and Lu. The bonding properties were assessed on the basis of natural atomic charges, Ln valence orbital populations, and analysis of bonding molecular orbitals.bonding, DFT, dinitrogen complexes, lanthanides, structure | INTRODUCTIONNitrogen fixation is the key step of the Haber-Bosch process developed in the first half of the 20th century. [1] The fixation procedure frees the nitrogen atoms from their triply bonded molecular (N 2 ) form. It is carried out by metalloenzymes (nitrogenases) in biological systems, while in the industry, metal catalysts are used for this purpose. The key point here is the chemisorption of N 2 on a metal catalyst's surface by charge transfer interactions between N 2 and the unsaturated valence shell of the metal.Due to the importance of fertilizers and other nitrogen-based compounds, considerable efforts are focused on the basic understanding of nitrogen fixation. A fundamental step in this research was the discovery of the first ruthenium dinitrogen complexes in the 1960s, followed by the synthesis of several other transition metal dinitrogen complexes. [2,3] For the catalytic reduction of N 2 , the coordinative unsaturated metal dinitrogen complexes are of the highest importance, which explains the ongoing considerable interest in them. [4][5][6][7][8][9] These complexes have generally low stability; therefore, they can be synthesized, isolated, and studied only under extreme conditions. A very efficient tool in this research proved to be the matrix isolation technique coupled mostly with vibrational spectroscopy. Examples of such successful experiments include the matrix-isolation infrared (IR) study of FeN 2 , [10] Ni(N 2 ) x (x = 1-4), [11][12][13][14][15][16] Pd(N 2 ) x (x = 1-3), [12] Pt(N 2 ) x (x = 1-3), [13] and rare earth dinitrogen complexes. [17][18][19][20] Quantum chemical calculations were entered early in the field confirming the structures and elucidating the bonding properties. Studies on transition metal complexes include FeN 2 , [21] Ni(N 2 ) x (x = 1-4), [14,16,[22][23][24] and WN x (x = 1-9). [25] The first theoretical study on lanthanide (holmium) dinitrogen complexes was performed by Ermilov et al [26] using the self-consistent-field SCF/3-21G level in conjunction with a 4f-in-valence pseudopotential [27] for Ho. Beyond the low computational level, further limitations of the study were the consideration of only quartet states and the size of up to six N 2 ligands. A recent study on La(N 2 ) x (x = 1-8) complexes showed that the generally small energy differences between the...

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Molecular oxides of high-valent actinides

Kovács

2020

Struct Chem

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The past decade has been very productive in the field of actinide (An) oxides containing high-valent An. Novel gas-phase experimental and an impressive number of theoretical studies have been performed, mostly on pure oxides or oxides extended with other ligands. The review covers the structural properties of molecular An oxides with high (An≥V) oxidation states. The presented compounds include the actinide dioxide cations [AnO2]+ and [AnO2]2+, neutral and ionic AnOx (x = 3–6), oxides with more than one An atom like neutral dimers, trimers and dimers from cation–cation interactions, as well as large U-oxide clusters observed very recently in the gaseous phase.

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Computational Methods: Lanthanides and Actinides

Abstract: First‐principles and semiempirical relativistic quantum chemical methods applicable to molecular systems containing lanthanides and actinides are briefly reviewed. Selected recent applications of some of these methods are discussed.

Cited by 3 publications

References 99 publications

Spin–orbit interaction with nonlinear wave functions

Spin–orbit interaction with nonlinear wave functions

Structure and bonding of lanthanide dinitrogen complexes, Ln(N₂)_1‐8

Molecular oxides of high-valent actinides

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Computational Methods: Lanthanides and Actinides

Abstract: First‐principles and semiempirical relativistic quantum chemical methods applicable to molecular systems containing lanthanides and actinides are briefly reviewed. Selected recent applications of some of these methods are discussed.

Cited by 3 publications

References 99 publications

Spin–orbit interaction with nonlinear wave functions

Spin–orbit interaction with nonlinear wave functions

Structure and bonding of lanthanide dinitrogen complexes, Ln(N2)1‐8

Molecular oxides of high-valent actinides

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Product

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Structure and bonding of lanthanide dinitrogen complexes, Ln(N₂)_1‐8