Density Functional Calculation of the Electric Field Gradient in Cadmium Complexes:  Comparison with Hartree−Fock, Second-Order Møller−Plesset, and Experimental Results

2000 ◽  
Vol 104 (25) ◽  
pp. 6047-6055 ◽  
Author(s):  
Jens Antony ◽  
Bjarne Hansen ◽  
Lars Hemmingsen ◽  
Rogert Bauer
Keyword(s):  
Electric Field ◽  
Electric Field Gradient ◽  
Field Gradient ◽  
Density Functional ◽  
Second Order ◽  
Experimental Results ◽  
Density Functional Calculation ◽  
Cadmium Complexes ◽  
Hartree Fock ◽  
Moller Plesset

AlN Nanotubes: A DFT Study of Al-27 and N-14 Electric Field Gradient Tensors

2007 ◽  
Vol 62 (12) ◽  
pp. 711-715 ◽  
Author(s):  
Ahmad Seif ◽  
Mahmoud Mirzaei ◽  
Mehran Aghaie ◽  
Asadollah Boshra
Keyword(s):  
Electric Field ◽  
Electric Field Gradient ◽  
Field Gradient ◽  
Density Functional ◽  
Quadrupole Coupling Constant ◽  
Basis Set ◽  
Basis Sets ◽  
B3lyp Method ◽  
Package Program ◽  
Nqr Parameters

Density functional theory (DFT) calculations were performed to calculate the electric field gradient (EFG) tensors at the sites of aliminium (27Al) and nitrogen (14N) nuclei in an 1 nm of length (6,0) single-walled aliminium nitride nanotube (AlNNT) in three forms of the tubes, i. e. hydrogencapped, aliminium-terminated and nitrogen-terminated as representatives of zigzag AlNNTs. At first, each form was optimized at the level of the Becke3,Lee-Yang-Parr (B3LYP) method, 6-311G∗∗ basis set. After, the EFG tensors were calculated at the level of the B3LYP method, 6-311++G∗∗ and individual gauge for localized orbitals (IGLO-II and IGLO-III) types of basis sets in each of the three optimized forms and were converted to experimentally measurable nuclear quadrupole resonance (NQR) parameters, i. e. quadrupole coupling constant (qcc) and asymmetry parameter (ηQ). The evaluated NQR parameters revealed that the considered model of AlNNT can be divided into four equivalent layers with similar electrostatic properties.With the exception of Al-1, all of the three other Al layers have almost the same properties, however, N layers show significant differences in the magnitudes of the NQR parameters in the length of the nanotube. Furthermore, the evaluated NQR parameters of Al-1 in the Al-terminated form and N-1 in the N-terminated form revealed the different roles of Al (base agent) and of N (acid agent) in AlNNT. All the calculations were carried out using the GAUSSIAN 98 package program.

Electric Field Gradients in Alkali Halide Molecules

1974 ◽  
Vol 52 (11) ◽  
pp. 2143-2156 ◽  
Author(s):  
Jean-Pierre Laplante ◽  
Andre D. Bandrauk
Keyword(s):  
Electric Field ◽  
Electric Field Gradient ◽  
Field Gradient ◽  
Alkali Halide ◽  
Electric Field Gradients ◽  
Calculated Density ◽  
Proper Understanding ◽  
Hartree Fock ◽  
Field Gradients ◽  
Classical Models

The electric field gradient q has been calculated from Hartree–Fock wavefunctions for the molecules LiF, LiCl, LiBr, NaF, NaCl, NaBr, KF, and KCl. It is found that σ and π electrons behave quite differently. Exchange distortions are of great importance for a proper understanding of σ contributions to q. Polarizations of π electrons into the bonding region are also considerable. These effects are responsible for failures of classical models and are further discussed using calculated density difference diagrams.

DENSITY FUNCTIONAL THEORY STUDY OF BINDING ENERGIES, 7Li NUCLEAR MAGNETIC SHIELDING, AND ELECTRIC FIELD GRADIENT TENSORS ON THE SMALL CLUSTERS OF LinHm (m ≤ n ≤ 4)

2007 ◽  
Vol 06 (04) ◽  
pp. 959-973 ◽  
Author(s):  
MEHDI D. ESRAFILI ◽  
FATEMEH ELMI ◽  
NASSER L. HADIPOUR
Keyword(s):  
Density Functional Theory ◽  
Electric Field ◽  
Electric Field Gradient ◽  
Field Gradient ◽  
Density Functional ◽  
Three Dimensional ◽  
Lithium Hydride ◽  
Binding Energies ◽  
Magnetic Shielding ◽  
Functional Theory

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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