An Investigation of Hydrogen-Bonding Effects on the Nitrogen and Hydrogen Electric Field Gradient and Chemical Shielding Tensors in the 9-Methyladenine Real Crystalline Structure:  A Density Functional Theory Study

The binding energies, geometries, 7 Li magnetic shielding, and electric field gradient tensors of hydrogenated lithium clusters, Li n H m (m ≤ n ≤ 4), were studied via density functional theory approach. We optimized the structures using B3LYP functional and 6-311++G (2d,2p) basis set. The calculated binding energies of lithium hydride clusters indicate that hydrogenation energy of Li n H m clusters decreases as the number of hydrogen atoms within the cluster increases. Our calculations also showed that for n = 4 clusters, the three-dimensional structure is more stable than the planar one. The study of the trends in the 7 Li magnetic shielding isotropy, σiso, and anisotropies, Δσ, values are explained in terms of the interplay between the electronic and geometrical effects. The variations in the 7 Li nuclear quadrupole coupling constants, χ, and their associated asymmetry parameters, ηQ, for different isomers of the lithium hydride clusters and the influence of hydrogenation on the EFG tensors are also discussed. For n = 4, we obtained a noticeable difference in the χ value from the planar to the three-dimensional structures. The atoms in molecules (AIM) analysis at the Li–H bond critical point reveals remarkably different topographical properties of the charge density and associated Laplacian fields for the planar and three-dimensional lithium hydride clusters.

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A study of hydrogen bond effects on the oxygen, nitrogen, and hydrogen electric field gradient tensors in the active site of human dehydroepiandrosterone sulphotransferase: A density-functional theory based treatment

Chemical Physics Letters ◽

10.1016/j.cplett.2016.04.001 ◽

2016 ◽

Vol 653 ◽

pp. 78-84 ◽

Cited By ~ 1

Author(s):

Elahe Astani ◽

Emran Heshmati ◽

Chun-Jung Chen ◽

Nasser L. Hadipour ◽

Setareh Shekarsaraei

Keyword(s):

Density Functional Theory ◽

Hydrogen Bond ◽

Electric Field ◽

Electric Field Gradient ◽

Field Gradient ◽

Active Site ◽

Density Functional ◽

Functional Theory

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Density functional theory-based electric field gradient database

Scientific Data ◽

10.1038/s41597-020-00707-8 ◽

2020 ◽

Vol 7 (1) ◽

Author(s):

Kamal Choudhary ◽

Jaafar N. Ansari ◽

Igor I. Mazin ◽

Karen L. Sauer

Keyword(s):

Density Functional Theory ◽

Electric Field ◽

Electric Field Gradient ◽

Field Gradient ◽

Density Functional ◽

Density Functional Theory Calculations ◽

Experimental Information ◽

Spectral Lines ◽

Functional Theory ◽

Link Type

Abstract The deviation of the electron density around the nuclei from spherical symmetry determines the electric field gradient (EFG), which can be measured by various types of spectroscopy. Nuclear Quadrupole Resonance (NQR) is particularly sensitive to the EFG. The EFGs, and by implication NQR frequencies, vary dramatically across materials. Consequently, searching for NQR spectral lines in previously uninvestigated materials represents a major challenge. Calculated EFGs can significantly aid at the search’s inception. To facilitate this task, we have applied high-throughput density functional theory calculations to predict EFGs for 15187 materials in the JARVIS-DFT database. This database, which will include EFG as a standard entry, is continuously increasing. Given the large scope of the database, it is impractical to verify each calculation. However, we assess accuracy by singling out cases for which reliable experimental information is readily available and compare them to the calculations. We further present a statistical analysis of the results. The database and tools associated with our work are made publicly available by JARVIS-DFT (https://www.ctcms.nist.gov/~knc6/JVASP.html) and NIST-JARVIS API (http://jarvis.nist.gov/).

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