The Nuclear Quadrupole Moment of 14N from Accurate Electric Field Gradient Calculations and Microwave Spectra of NP Molecule

2007 ◽  
Vol 72 (1) ◽  
pp. 64-82 ◽  
Author(s):  
Vladimir Kellö ◽  
Andrzej J. Sadlej
Keyword(s):  
Electric Field ◽  
Electric Field Gradient ◽  
Field Gradient ◽  
Quadrupole Moment ◽  
Quadrupole Coupling Constant ◽  
Basis Sets ◽  
Field Gradients ◽  
Nuclear Quadrupole Coupling Constant ◽  
Nuclear Quadrupole Moment ◽  
Nuclear Quadrupole

Extensive series of relativistic coupled cluster calculations of the electric field gradient at N in NP has been carried out. The accurate value of the calculated electric field gradient, combined with the highly accurate experimental value of the nuclear quadrupole coupling constant for the 14N nucleus, gives the 'molecular' value of the nuclear quadrupole moment Q(14N) = 20.46 mb. This result perfectly agrees with the value (20.44 ± 0.03 mb) determined from atomic calculations and atomic spectra. The present study involves also extensive investigations of basis sets which must be used in highly accurate calculations of electric field gradients.

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.

Nuclear Quadrupole Coupling Constant assignments for a series of azoles and azines by Hartree-Fock SCF-Cluster and Lattice Calculations

1996 ◽  
Vol 51 (5-6) ◽  
pp. 451-459 ◽  
Author(s):  
Michael H. Palmer
Keyword(s):  
Quadrupole Coupling Constant ◽  
Coupling Constants ◽  
Basis Sets ◽  
Coupling Constant ◽  
Hartree Fock ◽  
Field Gradients ◽  
Nuclear Quadrupole Coupling Constant ◽  
Quadrupole Coupling ◽  
Lattice Calculations ◽  
Nuclear Quadrupole

Abstract We present ab initio Hartree-Fock lattice calculations on a series of heterocyclic and other compounds. Some of these have previously been studied by cluster calculations with the same DZ basis sets at the SCF level. The electric field gradients at the nitrogen centres, are related to NQR experimental determinations of nuclear quadrupole coupling constants. The compounds studied include imidazole and pyrazole, 4-nitroimidazole, 4-nitropyrazole, pyrazine, and tetramethylpyrazine, pyridinium chloride, and N-methylpyridinium iodide, and pyridine-N-oxide.

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