An ab initio Study of the Molecular Electric-field Gradients of the Chlorsilanes

Abstract The electric field gradient (EFG) of chlorine in the chlorine containing silanes (SiCl4 , SiCl3H, SiCl2H2 , and SiClH3) was determined by means of ab initio methods and compared to recent experiments from which nuclear quadrupole moments are extracted. A careful estimation of the AO basis sets and the effect of the electron correlation is undertaken. The results showed the importance of the use of extended basis sets in the calculation of EFGs in second row atoms. Good agreement with deviations less than 5% from the experiments was found. The effect of the electron correlation was found to be small.

Download Full-text

The nuclear quadrupole moment of 69Ga and 115In

Canadian Journal of Chemistry ◽

10.1139/v09-017 ◽

2009 ◽

Vol 87 (7) ◽

pp. 802-805 ◽

Cited By ~ 3

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.

Download Full-text

The prediction of nuclear quadrupole moments from ab initio quantum chemical studies on small molecules. I. The electric field gradients at the 14N and 2H nuclei in N2, NO, NO+, CN, CN−, HCN, HNC, and NH3

The Journal of Chemical Physics ◽

10.1063/1.452390 ◽

1987 ◽

Vol 86 (12) ◽

pp. 6908-6917 ◽

Cited By ~ 71

Author(s):

Peter L. Cummins ◽

George B. Bacskay ◽

Noel S. Hush ◽

Reinhart Ahlrichs

Keyword(s):

Electric Field ◽

Small Molecules ◽

Quantum Chemical ◽

Quadrupole Moments ◽

Electric Field Gradients ◽

Field Gradients ◽

Chemical Studies ◽

Quantum Chemical Studies ◽

Nuclear Quadrupole ◽

Nuclear Quadrupole Moments

Download Full-text

Electric Field Gradients Around Point Defects in Metals

Zeitschrift für Naturforschung A ◽

10.1515/zna-1996-5-624 ◽

1996 ◽

Vol 51 (5-6) ◽

pp. 489-505

Author(s):

Alfred Seeger ◽

Jörg Ehmann ◽

Manfred Fähnle

Keyword(s):

Electric Field ◽

Ab Initio ◽

Density Functional ◽

Local Density ◽

Energy Levels ◽

Full Potential ◽

Good Resolution ◽

Quadrupole Moments ◽

Electric Field Gradients ◽

Field Gradients

The splittings of nuclear energy levels caused by the electric field gradients acting on the quadrupole moments of nuclei in the neighbourhood of atomic defects in cubic metals may serve as ‘‘fingerprints’’ providing us with a unique characterization of these defects. In favourable cases the NQDOR technique (n̲uclear q̲uadrupole d̲ouble r̲esonance) permits sensitive measurements of these splittings with good resolution. The present paper outlines the status of the ab-initio calculation of electric field gradients with emphasis on the theoretical basis (density functional theory with local density approximation) and on the techniques required for handling the specific problems associated with defects. Recent work by the supercell approach on atomic defects in Al and Cu, making use either of the full-potential linearized augmented-plane-wave method or of the ab-initio pseudopotential method, are reported and compared with experiments. The excellent agreement between experiment and theory for the field gradients acting on the nearest-neighbour nuclei of monovacancies in Al demonstrates the reliability and the potential of the theory.

Download Full-text

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

Zeitschrift für Naturforschung A ◽

10.1515/zna-1996-5-620 ◽

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.

Download Full-text

The prediction of nuclear quadrupole moments fromabinitioquantum chemical studies on small molecules. II. The electric field gradients at the17O,35Cl, and2H nuclei in CO, NO+, OH−, H2O, CH2O, HCl, LiCl, and FCl

The Journal of Chemical Physics ◽

10.1063/1.453586 ◽

1987 ◽

Vol 87 (1) ◽

pp. 416-423 ◽

Cited By ~ 44

Author(s):

Peter L. Cummins ◽

George B. Bacskay ◽

Noel S. Hush

Keyword(s):

Electric Field ◽

Small Molecules ◽

Quadrupole Moments ◽

Electric Field Gradients ◽

Field Gradients ◽

Chemical Studies ◽

Nuclear Quadrupole ◽

Nuclear Quadrupole Moments

Download Full-text

Electric Field Gradient in Aluminium due to Vacancy and Muon

Zeitschrift für Naturforschung A ◽

10.1515/zna-1992-1-210 ◽

1992 ◽

Vol 47 (1-2) ◽

pp. 45-48

Author(s):

M. J. Ponnambalam

Keyword(s):

Density Functional Theory ◽

Electric Field ◽

Density Functional ◽

Near Neighbour ◽

Electric Field Gradients ◽

Functional Theory ◽

Field Gradients ◽

Analytic Expression ◽

Valence Effect ◽

Good Agreement

AbstractThe electric field gradients (EFG) in aluminium due to a monovacancy and the interstitial muon are evaluated. The valence effect EFG qv is calculated using perturbed electron density δn(r)values obtained from density functional theory in an analytic expression which is valid at all distances from the impurity. The size effect EFG qs is evaluated using a new oscillatory form for the near neighbour (nn) displacements. The numerical values of qs are computed using fractional nn displacements available in the literature. For the total EFG good agreement with experiment is obtained without the use of any parameter.

Download Full-text