EPR and ENDOR Studies of Deuteron Hyperfine and Quadrupole Coupling in•CD(COOD)2:  Experimental and Theoretical Estimates of Electric Field Gradients from an α-Carbon

2000 ◽  
Vol 104 (27) ◽  
pp. 6372-6379 ◽  
Author(s):  
Audun Sanderud ◽  
Einar Sagstuen ◽  
Yoshiteru Itagaki ◽  
Anders Lund
Keyword(s):  
Electric Field ◽  
Electric Field Gradients ◽  
Field Gradients ◽  
Quadrupole Coupling

Quadrupole Coupling in some H-bonded Organic Systems by ab initio Lattice Calculations of Electric Field Gradients

1994 ◽  
Vol 49 (1-2) ◽  
pp. 146-154
Author(s):  
Michael H. Palmer ◽  
John A. Blair-Fish
Keyword(s):  
Electric Field ◽  
Ab Initio ◽  
Bulk Material ◽  
Electric Field Gradients ◽  
Hartree Fock ◽  
Organic Systems ◽  
Field Gradients ◽  
Quadrupole Coupling ◽  
Lattice Calculations ◽  
Distant Neighbour

Abstract We present ab initio Hartree-Fock lattice calculations performed in the unit cell environment, to compute a wave-function and the derived electric field gradients for the bulk material. These calculations differ from cluster calculations by including the effects of more distant neighbour molecules. Examples considered are ammonia, formamide, oxamide, urea, thiourea, uracil, para-banic acid, alloxan, guanidine bicarbonate and melamine.

17O Nuclear Quadrupole Coupling in Molecular and Lattice Systems by ab initio Calculation of Electric Field Gradients

1996 ◽  
Vol 51 (5-6) ◽  
pp. 442-450
Author(s):  
Michael H. Palmer
Keyword(s):  
Electric Field ◽  
Ab Initio ◽  
Test Site ◽  
Coupling Constants ◽  
Basis Sets ◽  
Electric Field Gradients ◽  
Lattice Systems ◽  
Field Gradients ◽  
Quadrupole Coupling ◽  
Nuclear Quadrupole

Abstract We present ab initio Hartree-Fock calculations of electric field gradients, which are related to experimental determinations of nuclear quadrupole coupling constants. The nucleus of special interest is 17O but other nuclei in the molecules, especially 14N, 2H and 33S are included. The calculations were performed (a) as single molecules either at the SCF and MP2 correlated levels, (b) as clusters of molecules about a test site, or (c) as lattice calculations computed in the unit cell environment. The basis sets are triple zeta valence plus polarisation in (a). Because of limitations in exponent range in (c), the bases in both (b) and (c), where comparison was sought, are DZ at the SCF level.

Assignment and structural dependence of electric field gradients in anorthite and simple field gradient calculations in some aluminosilicates

1974 ◽  
Vol 140 (5-6) ◽  
Author(s):  
J. L. Staehli ◽  
D. Brinkmann
Keyword(s):  
Electric Field ◽  
Field Gradient ◽  
Quadrupole Coupling Constant ◽  
Coupling Constant ◽  
Electric Field Gradients ◽  
Point Charge Model ◽  
Polarization Effects ◽  
Field Gradients ◽  
Charge Model ◽  
Quadrupole Coupling

AbstractThe electric field gradient tensors at theIt was found that the quadrupole coupling constant is correlated with the distortion of the coordination tetrahedra and that the simple point-charge model which neglects polarization effects is apt to yield quite satisfying results for very distorted tetrahedra.Similar results were obtained for the Al and Na sites in albite, NaAlSi

Quadrupole Coupling in Purines and Pyrimidines by Hartree-Fock Lattice Calculations of Electric Field Gradients

1996 ◽  
Vol 51 (5-6) ◽  
pp. 479-488
Author(s):  
Michael H. Palmer
Keyword(s):  
Electric Field ◽  
Coupling Constants ◽  
Basis Sets ◽  
Electric Field Gradients ◽  
Hartree Fock ◽  
Field Gradients ◽  
Double Zeta ◽  
Quadrupole Coupling ◽  
Lattice Calculations ◽  
Protonated Cytosine

Abstract We present ab initio Hartree-Fock lattice calculations on adenine, guanine and hypoxanthine, and some pyrimidines, including cytosine and uracil derivatives. The electric field gradients at the nitrogen centres are related to NQR experimental determinations of nuclear quadrupole coupling constants. The calculations were performed as lattice calculations in the unit cell environment, with 6-31G or double zeta basis sets at the SCF level. The present analysis strongly suggests that χzz at N3 in cytosine, N3 in guanine are both positive, and approximately tangential to the ring at that centre. In contrast, N7 in guanine is like most other azine-type N centres, with a largely radial direction for χzz. The 3-protonated cytosine ring has χzz as the local π-direction.

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