The Calculation of Electric Field Gradients byab initioMethods, and Their Relationship to Experimental Nuclear Quadrupole Coupling Constants

2005 ◽  
Author(s):  
Michael H. Palmer
Keyword(s):  
Electric Field ◽  
Coupling Constants ◽  
Electric Field Gradients ◽  
Field Gradients ◽  
Quadrupole Coupling ◽  
Nuclear Quadrupole

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.

The nuclear quadrupole moment of 69Ga and 115In

2009 ◽  
Vol 87 (7) ◽  
pp. 802-805 ◽  
Author(s):  
Hana Yakobi ◽  
Ephraim Eliav ◽  
Uzi Kaldor
Keyword(s):  
Electric Field ◽  
Fock Space ◽  
Coupling Constants ◽  
Basis Sets ◽  
Coupled Cluster ◽  
Quadrupole Moments ◽  
Electric Field Gradients ◽  
Field Gradients ◽  
Nuclear Quadrupole ◽  
Nuclear Quadrupole Moments

Electric field gradients at the nuclei of gallim and indium are determined by finite field calculations of the atomic energies as functions of the nuclear quadrupole moments. The four-component Dirac–Coulomb–Gaunt Hamiltonian serves as framework, and all electrons are correlated by Fock-space coupled cluster with single and double excitations or by single reference coupled cluster with approximate triples. Large, converged basis sets (e.g., 28s24p20d13f5g4h for In) and virtual spaces are used. Together with experimental nuclear quadrupole coupling constants, known with high precision, the calculated electric field gradients yield the nuclear quadrupole moments. For 69Ga, we get Q = 174(3) mb, in agreement with the earlier 171(2) mb obtained from molecular calculations. The 115In moment is Q = 772(5) mb, considerably lower than the previously accepted 810 mb, and in good agreement with the recent molecular value of 770(8) mb.

The ab initio Calculation of Nuclear Quadrupole Coupling Constants and their Comparison with Experiment

1990 ◽  
Vol 45 (3-4) ◽  
pp. 357-367 ◽  
Author(s):  
Michael H. Palmer
Keyword(s):  
Ab Initio ◽  
Single Molecule ◽  
Ab Initio Calculation ◽  
Coupling Constants ◽  
Structural Variations ◽  
Electric Field Gradients ◽  
Field Gradients ◽  
Comparison With Experiment ◽  
Quadrupole Coupling ◽  
Nuclear Quadrupole

Abstract Ab initio calculations of electric field gradients (EFG) and conversion to nuclear quadrupole coupling constants (NQCC) are described, with particular reference to 14 N and 10,11B. The correlation of EFG and NQCC for a series of boranes leads to the value 8.32 MHz/a.u. (0.0354 barn) for Q(11B). The structural variations of these microwave and single molecule calculations of 10,11 B NQCC are discussed.

Microwave Spectra of Furazan II. Nuclear Quadrupole Coupling in d1-Furazan

1988 ◽  
Vol 43 (6) ◽  
pp. 607-613 ◽  
Author(s):  
Otto L. Stiefvater
Keyword(s):  
Structural Information ◽  
Radial Electric Field ◽  
Coupling Constants ◽  
Molecular Orbital Calculations ◽  
Electric Field Gradients ◽  
Field Gradients ◽  
Quadrupole Coupling ◽  
Nuclear Quadrupole ◽  
Data Yield ◽  
Preceding Study

Abstract The nuclear quadrupole coupling constants for the two nitrogen atoms in monodeuterated furazan (C2HDN2O) were determined from the hyperfine structure of eight rotational transitions with low J-values. The coupling constants along the inertial axes are: χaa (2) = + 3.546(10) MHz, χaa (5) = -5.044(10) MHz, χbb (2) = -4.690(10) MHz, χbb (5) = + 3.900(10) MHz, χcc (2) = + 1.144(10) MHz, χcc (5) = + 1.144(10) MHz. In conjunction with structural information from the preceding study, these data yield the principal coupling constants, with 3er-uncertainties, as: χR(2/5) = - 5.53 (4) MHz, χT(2/5) = + 4.39(4)MHz, χR(2/5) = + 1.14(4) MHz. The radial electric field gradients deviate from the direction of the external bisector of the ring angle ONC by 24.6° towards the oxygen atom. These results are in qualitative agreement with previous work by NQR spectroscopy and with the results of ab initio molecular orbital calculations.

Spektroskopische Untersuchungen in der Festkörperchemie, XIII. Temperaturabhängigkeit der 127I-Kernquadrupolkopplung in NH4IO4 und anderen Periodaten / Spectroscopic Investigations in the Solid State Chemistry, XIII. Temperature Dependence of the 127I-Nuclear Quadrupole Coupling in NH4IO4 and other Periodates

1980 ◽  
Vol 35 (11) ◽  
pp. 1349-1354 ◽  
Author(s):  
Paul K. Burkert
Keyword(s):  
Temperature Dependence ◽  
Coupling Constants ◽  
Solid State Chemistry ◽  
Positive Temperature ◽  
Electric Field Gradients ◽  
Field Gradients ◽  
Quadrupole Coupling ◽  
Temperature Dependences ◽  
Nuclear Quadrupole ◽  
Nmr Signals

The temperature dependence of the electric field gradients was measured by I. and II. order quadrupole effects of the 127I NMR signals in scheelite-structured NH4IO4 and RbIO4, in pseudo-scheelite CsIO4 and in N(CH3)4IO4, where rcation > ranion- An interpretation of the anomalous positive temperature dependences of the quadrupole coupling constants in NH4IO4 and in the isostructural NH4ReO4 is proposed.

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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